Hydroformylation

ABSTRACT

The present invention relates to a process for hydroformylating in the presence of a catalyst comprising at least one complex of a metal of transition group VIII with mono-phosphorus compounds which are capable of dimerizing via noncovalent bonds as ligands, to such catalysts and to their use.

[0001] The present invention relates to a process for hydroformylatingolefins in the presence of a catalyst comprising at least one complex ofa metal of transition group VIII having monophosphorus compounds capableof dimerizing via noncovalent bonds as ligands, to such catalysts and totheir use.

[0002] The hydroformylation or oxo process is an important large-scaleindustrial process and serves to prepare aldehydes from olefins, carbonmonoxide and hydrogen. These aldehydes may optionally be hydrogenated inthe same procedure with hydrogen to give the corresponding oxo alcohols.The reaction itself is strongly exothermic and generally proceeds underelevated pressure and at elevated temperatures in the presence ofcatalysts. The catalysts used are Co, Rh, Ir, Ru, Pd or Pt compounds orcomplexes which may be modified with nitrogen or phosphorus ligands toinfluence the activity and/or selectivity. As a consequence of thepossible addition of CO to each of the two carbon atoms of a doublebond, the hydroformylation reaction of olefins having more than twocarbon atoms may result in the formation of mixtures of isomericaldehydes. In addition, the use of olefins having at least four carbonatoms may also result in double bond isomerization, i.e. internal doublebonds shifting to a terminal position and vice versa.

[0003] As a consequence of the significantly greater industrialsignificance of the α-aldehydes and in particular of the n-aldehydes,there is a drive to optimize hydroformylation catalysts to achieve veryhigh hydroformylation activity with simultaneously very low tendency toform non-α- and especially non-n-aldehydes.

[0004] For example, for the preparation of ester plasticizers havinggood performance properties, there is a demand for plasticizer alcoholshaving from about 6 to 12 carbon atoms and a certain degree of branching(known as semilinear alcohols) and for corresponding mixtures thereof.These include in particular 2-propylheptanol and alcohol mixturescomprising it. To prepare it, for example, C₄-hydrocarbon mixtures whichcomprise butenes or butenes and butanes may be subjected to ahydroformylation and subsequent aldol condensation. Wherehydroformylation catalysts are used which have insufficientn-selectivity, the hydroformylation may readily result in the formationof undesired product aldehydes, which makes the entire process lesseconomically viable.

[0005] In low-pressure rhodium hydroformylation, the use of phosphorusligands to stabilize and/or activate the catalyst metal is known.Suitable phosphorus ligands are, for example, phosphines, phosphinites,phosphonites, phosphites, phosphoramidites, phospholes andphosphabenzenes. The currently most widely used ligands aretriarylphosphines, for example triphenylphosphine and sulfonatedtriphenylphosphine, since these have sufficient stability under thereaction conditions. However, a disadvantage of these ligands is thatonly very high ligand excesses generally afford satisfactory yields,especially of linear aldehydes.

[0006] It is also known that the use of chelate ligands which have twophosphorus groups capable of coordinating has an advantageous effect onthe n-selectivity achieved (see Moulijn, van Leeuwen and van Santen,Catalysis, Vol. 79, p. 199-248, Elsevier 1993). However, a disadvantageof the use of chelate ligands is that complicated syntheses are requiredto prepare them in many cases and/or they can only be obtained in pooryields. There is therefore still a need for readily available ligandsfor hydroformylation catalysts which enable hydroformylation with highn-selectivity.

[0007] In J. Org. Chem. 2000, 65, p. 6917-6921, M. Akazome et al.describe the synthesis, solid state structure and the aggregationbehavior of phosphines which bear a 2-pyridone ring. There is nodescription of use as ligands for transition metal complexes.

[0008] In J. Org. Chem. 1978, 43, p. 947-949, G. R. Newkome and D. C.Hager describe a process for preparing pyridyldiphenylphosphines. Thisdocument likewise does not describe use as ligands in transition metalcatalysts.

[0009] U.S. Pat. No. 4,786,443 and U.S. Pat. No. 4,940,787 describeprocesses for carbonylating acetylenically unsaturated compounds in thepresence of a palladium catalyst. Ligands used are phosphines which bearat least one hetaryl radical, for example an optionally substitutedpyridyl radical. The use as ligands of phosphines which have at leastone group capable of forming noncovalent bonds is not described.

[0010] WO 80/01690 describes a rhodium catalyst which includes at leastone phosphine ligand in which two aryl groups and, via an alkylenebridge, a heteroatom-containing radical are bonded to the phosphorusatom. The heteroatom-containing radical may be a multitude of differentradicals, and some of the radicals mentioned contain carboxamide groups.However, this document does not teach the use of ligands having afunctional group which is capable of forming intermolecular noncovalentbonds. For instance, the only example of carboxamide-containing ligandsis (N-2-pyrolidinonyl-ethyl)diphenylphosphine, which is not capable offorming intermolecular noncovalent bonds between the amide groups. U.S.Pat. No. 4,687,874 has a comparable disclosure content to WO 80/01690.

[0011] A publication, published after the priority date of the presentinvention, of B. Breit and W. Seiche in J. Am. Chem. Soc. 2003, 125,6608-6609 describes the dimerization of monodentate ligands via hydrogenbonds to form bidentate donor ligands and their use in hydroformylationcatalysts having high regioselectivity.

[0012] The unpublished German patent application 103 55 066.6 describesa process for preparing chiral compounds in the presence of a catalystwhich comprises at least one transition metal complex having ligandswhich have functional groups capable of forming intermolecular,noncovalent bonds.

[0013] It is an object of the present invention to provide ahydroformylation process which is suitable for hydroformylating1-olefins with high n-selectivity. In the process, hydroformylationcatalysts should preferably be used whose ligands can be preparedreadily and in good yields. The catalysts should have a high selectivityin favor of the hydroformylation compared to the hydrogenation, and/orenable a high space-time yield. They should in particular also affordgood yields of linear aldehydes with lower ligand excesses compared tothe catalyst metal than in the case of the prior art catalysts.

[0014] We have found that this object is achieved by the use ofmonophosphorus ligands which are capable of forming intermolecularnoncovalent bonds. Such ligands may in principle dimerize viaintermolecular noncovalent bonds and thus form pseudochelate complexes.

[0015] The present invention therefore provides a process forhydroformylating compounds which contain at least one ethylenicallyunsaturated double bond by reacting with carbon monoxide and hydrogen inthe presence of a catalyst comprising at least one complex of a metal oftransition group VIII of the Periodic Table of the Elements with ligandswhich each have a phosphorus group and at least one functional groupwhich is capable of forming intermolecular noncovalent bonds, whereinthe complex has ligands which are dimerized via intermolecularnoncovalent bonds and wherein the distance between the phosphorus atomsof the dimerized ligands is at most 5 Å.

[0016] The present invention also relates to catalysts comprisingcomplexes with a metal of transition group VIII of the Periodic Table ofthe Elements which comprise ligands which have a phosphorus group and atleast one functional group capable of forming intermolecular noncovalentbonds.

[0017] The invention further provides a process for preparing2-propylheptanol, which comprises the hydroformylation of butene, analdol condensation of the hydroformylation products obtained in this wayand the subsequent hydrogenation of the condensation products, using acomplex of a metal of transition group VIII with the above-describedligands as the hydroformylation catalyst.

[0018] It has been found that the use in hydroformylation ofmonophosphorus ligands (ligands which have only one phosphorus group permolecule) which are capable of forming dimers via intermolecularnoncovalent bonds, and in which the distance between the two phosphorusatoms is in a range which is customary for chelate ligands, results inan n-selectivity being achieved which is so high as to otherwise only beachieved with chelate ligands. Ligands having the capability of formingdimers via intermolecular noncovalent bonds are also referred to in thedescription as pseudochelate ligands.

[0019] According to the invention, ligands are used which have afunctional group which is capable of forming intermolecular noncovalentbonds. These bonds are preferably hydrogen bonds or ionic bonds, inparticular hydrogen bonds. In a preferred embodiment, the functionalgroups may be groups capable of tautomerizing. The functional groupscapable of forming intermolecular noncovalent bonds make the ligandscapable of associating, i.e. of forming aggregates in the form ofdimers.

[0020] In the context of the present invention, a pair of functionalgroups of two ligands which are capable of forming intermolecularnoncovalent bonds is referred to as “complementary functional groups”.“Complementary compounds” are ligands/ligand pairs which have mutuallycomplementary functional groups. Such pairs are capable of associating,i.e. of forming aggregates.

[0021] The functional groups capable of forming intermolecularnoncovalent bonds are preferably selected from hydroxyl, primary,secondary and tertiary amino, thiol, keto, thioketone, imine, carboxylicester, carboxamide, amidine, urethane, urea, sulfoxide, sulfoximime,sulfonamide and sulfonic ester groups.

[0022] These functional groups are preferably self-complementaryfunctional groups, i.e. the noncovalent bonds are formed between twoidentical functional groups of the ligands used. When there is only onetype of ligands which form ligand/ligand pairs, these are referred to as“homo-dimers”. Functional groups which are capable of tautomerizing mayeach be present in the dimers in the form of identical or differentisomers (tautomers). For example, in the case of keto-enoltautomerization, both monophosphorus ligands may be in the keto form,both in the enol form or one in the keto form and one in the enol form.

[0023] In a further suitable embodiment, at least two different ligandsare used in the process according to the invention and have functionalgroups capable of forming inter-molecular, noncovalent bonds. In thiscase, different ligands exclusively or at least partly form theligand/ligand pairs (known as “hetero-dimers”). The functional groups ofthe two different ligands which form the noncovalent bond may beidentical or different groups. Functional groups which are capable oftautomerizing may each be present in the dimers in the form of the sameor as different isomers (tautomers). The molar ratio of the two ligandswhich form the heterodimer is preferably in the range from 30:1 to 1:30.

[0024] The distance between phosphorus atoms of the dimerized ligands ispreferably in the range from 2.5 to 4.5 Å, more preferably from 3.5 to4.2 Å. Especially suitable is a distance between the phosphorus atoms offrom 3.6 to 4.1 Å, for example from 3.7 to 4.0 Å.

[0025] Suitable methods for determining whether the ligands used arecapable of forming dimers include crystal structure analysis, NMRspectroscopy and molecular modeling methods. For the determination, itis generally sufficient to use the ligands in uncomplexed form. This isespecially true for molecular modeling methods. It has additionally beenfound that crystal structure analysis in the solid state and NMRspectroscopy in solution and calculation of the structure for the gasphase generally all achieve reliable forecasts of the behavior of theligands used under the hydro-formylation conditions. For instance,ligands which are capable of forming dimers by the determination methodsmentioned generally have properties under hydro-formylation conditionsas are otherwise customary only for chelate ligands. These include inparticular the achievement of high n-selectivity in the hydroformylationof 1-olefins. It has also been found that this high n-selectivity is nolonger achieved when the formation of intermolecular noncovalent bondsbetween the ligands is disrupted in the hydroformylation by adding acidsor protic solvents, for example methanol.

[0026] In a suitable procedure for determining whether a ligand issuitable for the process according to the invention, a graphic molecularmodeling program is initially used to generate all possiblehydrogen-bonded dimers of the ligand and its tautomers. These dimerstructures are then optimized by quantum chemistry methods. For thispurpose, preference is given to using density functional theory (DFT),for example using the functional B-P86 (A. D. Becke, Phys. Rev. A 1988,38, 3098; J. P. Perdew, Phys. Rev. B 1986, 33, 8822; ibid 1986, 34,7406(E)) and the basis SV(P) (A. Schäfer, H. Horn, R. Ahlrichs, J. Chem.Phys. 1992, 97, 2571) in the Turbomole program package (R. Ahlrichs, M.Bär, M. Häser, H. Horn, C. Kölmel, Chem. Phys. Lett. 1989, 162, 165; M.v. Arnim, R. Ahlrichs; J. Comput. Chem. 1998, 19, 1746) (obtainable fromthe University of Karlsruhe). A commercially available suitablemolecular modeling package is Gaussian 98 (M. J. Frisch, J. A. Pople etal., Gaussian 98, Revision A.5, Gaussian Inc., Pittsburgh (Pa.) 1998).

[0027] Suitable pseudochelate ligands are only those in which thedistance between the phosphorus atoms in the calculated dimer structureis less than 5 Å.

[0028] For the purpose of illustrating the present invention, the term“alkyl” encompasses straight-chain and branched alkyl groups. These arepreferably straight-chain or branched C₁-C₂₀-alkyl, more preferablyC₁-C₁₂-alkyl, particularly preferably C₁-C₈-alkyl and very particularlypreferably C₁-C₄-alkyl groups. Examples of alkyl groups are inparticular methyl, ethyl, propyl, isopropyl, n-butyl, 2-butyl,sec-butyl, tert-butyl, n-pentyl, 2-pentyl, 2-methylbutyl, 3-methylbutyl,1,2-dimethylpropyl, 1,1-dimethylpropyl, 2,2-dimethylpropyl,1-ethylpropyl, n-hexyl, 2-hexyl, 2-methylpentyl, 3-methylpentyl,4-methylpentyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 2,3-dimethylbutyl,1,1-dimethyl-butyl, 2,2-dimethylbutyl, 3,3-dimethylbutyl,1,1,2-trimethylpropyl, 1,2,2-trimethylpropyl, 1-ethylbutyl,2-ethylbutyl, 1-ethyl-2-methylpropyl, n-heptyl, 2-heptyl, 3-heptyl,2-ethylpentyl, 1-propylbutyl, n-octyl, 2-ethylhexyl, 2-propylheptyl,nonyl, decyl.

[0029] The term “alkyl” also encompasses substituted alkyl groups whichgenerally have 1, 2, 3, 4 or 5, preferably 1, 2 or 3 and more preferably1, substituent(s). These are preferably selected from cycloalkyl, aryl,hetaryl, halogen, NE¹E², NE¹E²E³⁺, carboxylate and sulfonate. Apreferred perfluoroalkyl group is trifluoromethyl.

[0030] In the context of the present invention, the term “alkylene”refers to straight-chain or branched alkanediyl groups having from 1 to5 carbon atoms.

[0031] In the context of the present invention, the term “cycloalkyl”refers to unsubstituted and also substituted cycloalkyl groups,preferably C₅-C₇-Cycloalkyl groups, such as cyclopentyl, cyclohexyl orcycloheptyl. In the case of substitution, these generally bear 1, 2, 3,4 or 5, preferably 1, 2 or 3 and more preferably 1, substituent(s).These substituents are preferably selected from alkyl, alkoxy andhalogen.

[0032] In the context of the present invention, the term“heterocycloalkyl” encompasses saturated, cycloaliphatic groups havinggenerally from 4 to 7, preferably 5 or 6, ring atoms, in which 1 or 2 ofthe ring carbon atoms are replaced by heteroatoms selected from theelements oxygen, nitrogen and sulfur and which may optionally besubstituted, and in the case of substitution, these heterocycloaliphaticgroups may bear 1, 2 or 3, preferably 1 or 2, more preferably 1,substituent(s). These substituents are preferably selected from alkyl,aryl, COOR^(o), COO⁻M⁺ and NE¹E², particular preference is given toalkyl radicals. Examples of such heterocycloaliphatic groups includepyrrolidinyl, piperidinyl, 2,2,6,6-tetramethylpiperidinyl,imidazolidinyl, pyrazolidinyl, oxazolidinyl, morpholidinyl,thiazolidinyl, isothiazolidinyl, isoxazolidinyl, piperazinyl,tetrahydrothiophenyl, tetrahydrofuranyl, tetrahydropyranyl, dioxanyl.

[0033] In the context of the present invention, the term “aryl” refersto substituted and also unsubstituted aryl groups, and is preferablyphenyl, tolyl, xylyl, mesityl, naphthyl, fluorenyl, anthracenyl,phenanthrenyl or naphthacenyl, more preferably phenyl or naphthyl, andin the case of substitution, these aryl groups may generally bear 1, 2,3, 4 or 5, preferably 1, 2 or 3 and more preferably 1, substituent(s)which is/are selected from the groups of alkyl, alkoxy, carboxylate,trifluoromethyl, sulfonate, NE¹E², alkylene-NE¹E², nitro, cyano orhalogen. A preferred perfluoroaryl group is pentafluorophenyl.

[0034] In the context of the present invention, the term “hetaryl”encompasses unsubstituted or substituted, heterocycloaromatic groups,preferably the pyridyl, quinolinyl, acridinyl, pyridazinyl, pyrimidinyl,pyrazinyl, pyrrolyl, imidazolyl, pyrazolyl, indolyl, purinyl, indazolyl,benzotriazolyl, 1,2,3-triazolyl, 1,3,4-triazolyl and carbazolyl groups.In the case of substitution, these heterocycloaromatic groups may bear1, 2 or 3 substituents which are selected from the groups of alkyl,alkoxy, carboxylate, sulfonate, NE¹E², alkylene-NE¹E² or halogen.

[0035] In the context of this invention, carboxylate and sulfonate arepreferably a derivative of a carboxylic acid function or of a sulfonicacid function respectively, in particular a metal carboxylate orsulfonate, a carboxylic ester or sulfonic ester function or acarboxamide or sulfonamide function. These include, for example, theesters with C₁-C₄-alkanols, such as methanol, ethanol, n-propanol,isopropanol, n-butanol, sec-butanol and tert-butanol.

[0036] The above illustrations of the terms “alkyl”, “cycloalkyl”,“aryl”, “heterocycloalkyl” and “hetaryl” apply correspondingly to theterms “alkoxy”, “cycloalkoxy”, “aryloxy”, “heterocycloalkoxy” and“hetaryloxy”.

[0037] In the context of the present invention, the term “acyl” refersto alkanoyl or aroyl groups having generally from 2 to 11, preferablyfrom 2 to 8, carbon atoms, for example the acetyl, propanoyl, butanoyl,pentanoyl, hexanoyl, heptanoyl, 2-ethylhexanoyl, 2-propylheptanoyl,pivaloyl, benzoyl or naphthoyl groups.

[0038] The NE¹E², NE⁴E⁵ and NE⁷E⁸ groups are preferablyN,N-dimethylamino, N,N-diethyl-amino, N,N-dipropylamino,N,N-diisopropylamino, N,N-di-n-butylamino, N,N-di-t-butyl-amino,N,N-dicyclohexylamino or N,N-diphenylamino.

[0039] Halogen is fluorine, chlorine, bromine and iodine, preferablyfluorine, chlorine and bromine.

[0040] M⁺ is one cation equivalent, i.e. a monovalent cation or thefraction of a polyvalent cation corresponding to a single positivecharge. The M⁺ cation merely serves as the counterion to neutralizenegatively charged substituent groups, such as the COO⁻ or the sulfonategroup, and may in principle be selected arbitrarily. Preference istherefore given to using alkali metal, in particular Na⁺, K⁺, Li⁺ ions,or onium ions such as ammonium, mono-, di-, tri-, tetraalkylammonium,phosphonium, tetraalkylphosphonium or tetraarylphosphonium ions.

[0041] The same applies to the anion equivalent X⁻ which merely servesas the counterion of positively charged substituent groups, such as theammonium groups, and may be selected arbitrarily among monovalent anionsand the fractions of a polyvalent anion corresponding to a singlenegative charge, and preference is generally given to halide ions X⁻, inparticular chloride and bromide.

[0042] The values for x and y are each an integer from 1 to 240,preferably an integer from 3 to 120.

[0043] In the context of the present invention, the term “polycycliccompound” encompasses in the widest sense compounds which contain atleast two rings, irrespective of how these rings are joined. These maybe carbocyclic and/or heterocyclic rings. The rings may be joined viasingle or double bonds (“multiring compounds”), connected by fusion(“fused ring systems”) or bridged (“bridged ring systems”, “cagecompounds”). Preferred polycyclic compounds are fused ring systems.

[0044] Fused ring systems may be aromatic, hydroaromatic and cycliccompounds joined (fused on) by fusing. Fused ring systems consist oftwo, three or more than three rings. Depending on the type of joining, adistinction is drawn in fused ring systems between ortho-fusing, i.e.each ring has in each case one edge, i.e. two common atoms, with eachneighboring ring, and peri-fusing, in which one carbon atom belongs tomore than two rings. Among the fused ring systems, preference is givento ortho-fused ring systems.

[0045] The ligand/ligand pairs used in accordance with the invention canbe schematically illustrated as follows:

[0046] where

[0047] A and B are radicals having mutually complementary functionalgroups, between which there is a noncovalent interaction,

[0048] R¹ and R² are as defined hereinbelow.

[0049] The phosphorus group is preferably selected from groups of thegeneral formula

[0050] where

[0051] R¹ and R² are each independently alkyl, alkoxy, cycloalkyl,cycloalkoxy, heterocycloalkyl, heterocycloalkoxy, aryl, aryloxy, hetarylor hetaryloxy, or

[0052] R¹ and R² together with the phosphorus atom to which they arebonded are each a 5- to 8-membered heterocycle which may optionallyadditionally be singly, doubly or triply fused with cycloalkyl,heterocycloalkyl, aryl or hetaryl, and the heterocycle and, wherepresent, the fused groups may each independently bear one, two, three orfour substituents which are selected from alkyl, cycloalkyl,heterocycloalkyl, aryl, hetaryl, COOR^(c), COO⁻M⁺, SO₃R^(c), SO₃ ⁻M⁺,PO₃(R^(c))(R^(d)), (PO₃)²⁻(M⁺)₂, NE⁴E⁵, (NE⁴E⁵E⁶)⁺X⁻, OR^(e), SR^(e),(CHR^(f)CH₂O)_(y)R^(e), (CH₂NE⁴)_(y)R^(e), (CH₂CH₂NE⁴)_(y)R^(e),halogen, nitro, acyl or cyano,

[0053] where

[0054] R^(c) and R^(d) are each identical or different radicals selectedfrom alkyl, cycloalkyl, aryl and hetaryl,

[0055] R^(e), E⁴, E⁵, E⁶ are each identical or different radicalsselected from hydrogen, alkyl, cycloalkyl, acyl, aryl and hetaryl,

[0056] R^(f) is hydrogen, methyl or ethyl,

[0057] M⁺ is one cation equivalent,

[0058] X⁻ is one anion equivalent and

[0059] y is an integer from 1 to 240.

[0060] In a first preferred embodiment, R¹ and R² are not joinedtogether. In that case, R¹ and R² are preferably each independentlyselected from alkyl, cycloalkyl, aryl and hetaryl, as defined at theoutset.

[0061] Preferably, at least one of the R¹ and R² radicals, and morepreferably R¹ and R² are both aryl, in particular both phenyl.

[0062] In addition, preference is given to at least one of the R¹ and R²radicals being a pyrrole group bonded to the phosphorus atom via thepyrrolic nitrogen atom. R¹ and R² are preferably both a pyrrole groupbonded to the phosphorus atom via the pyrrolic nitrogen atom, and R¹ andR² may be identical or different pyrrole groups.

[0063] In the context of the present invention, the term “pyrrole group”refers to a series of unsubstituted or substituted, heterocycloaromaticgroups which are structurally derived from the basic pyrrole structureand contain a pyrrolic nitrogen atom in the heterocycle which may becovalently joined to a phosphorus atom. The term “pyrrole group” thusencompasses the unsubstituted or substituted pyrrolyl, imidazolyl,pyrazolyl, indolyl, purinyl, indazolyl, benzotriazolyl, 1,2,3-triazolyl,1,3,4-triazolyl and carbazolyl groups which, in the case ofsubstitution, may generally bear 1, 2 or 3, preferably 1 or 2, morepreferably 1, substituent(s), selected from the groups of alkyl, alkoxy,acyl, carboxylate, sulfonate, NE⁴E⁵, alkylene-NE⁴E⁵ or halogen.Preferred pyrrole groups are 3-(C₁-C₄-alkyl)indolyl groups, such as the3-methylindolyl group (skatolyl group).

[0064] In a further preferred embodiment, R¹ and R² are joined together.In that case, the phosphorus group is preferably a group of the formula

[0065] where

[0066] r and s are each independently 0 or 1, and

[0067] D together with the phosphorus atom and the oxygen atom(s) towhich it is bonded is a 5- to 8-membered heterocycle which is optionallysingly, doubly or triply fused with cycloalkyl, heterocycloalkyl, aryland/or hetaryl, and the fused groups may each independently bear one,two, three or four subtituents selected from alkyl, alkoxy, halogen,sulfonate, NE⁴E⁵, alkylene-NE⁴E⁵, nitro, cyano and carboxylate, and/or Dmay have one two or three substituents which are selected from alkyl,alkoxy, optionally substituted cycloalkyl and optionally substitutedaryl, and/or D may be interrupted by one, two or three optionallysubstituted heteroatoms.

[0068] The D radical is preferably a C₂- to C₆-alkylene bridge which issingly or doubly fused with aryl and/or may have a substituent which isselected from alkyl, optionally substituted cycloalkyl and optionallysubstituted aryl, and/or may be interrupted by an optionally substitutedheteroatom.

[0069] The fused aryls of the D radicals are preferably benzene ornaphthalene. Fused benzene rings are preferably unsubstituted or have 1,2 or 3, in particular 1 or 2, substituents which are preferably selectedfrom alkyl, alkoxy, halogen, sulfonate, NE⁴E⁵, alkylene-NE⁴E⁵,trifluoromethyl, nitro, carboxylate, alkoxycarbonyl, acyl and cyano.Fused naphthalenes are preferably unsubstituted or have, in the nonfusedring and/or in the fused ring, in each case 1, 2 or 3, in particular 1or 2, of the substituents mentioned above for the fused benzene rings.In the substituents of the fused aryls, alkyl is preferably C₁- toC₄-alkyl and in particular methyl, isopropyl and tert-butyl. Alkoxy ispreferably C₁- to C₄-alkoxy and in particular methoxy. Alkoxycarbonyl ispreferably C₁- to C₄-alkoxycarbonyl.

[0070] When the C₂- to C₆-alkylene bridge of the D radical isinterrupted by one, two or three optionally substituted heteroatoms,they are preferably selected from O, S and NR^(h) where R^(h) is alkyl,cycloalkyl or aryl.

[0071] When the C₂- to C₆-alkylene bridge of the D radical issubstituted, it preferably has 1, 2 or 3, in particular 1,substituent(s) which is/are selected from alkyl, cycloalkyl,heterocycloalkyl, aryl and hetaryl, and the cycloalkyl,heterocycloalkyl, aryl and hetaryl substituents may each bear 1, 2 or 3of the substituents mentioned as suitable for these radicals at theoutset.

[0072] The D radical is preferably a C₃- to C₆-alkylene bridge which isfused as described above and/or substituted and/or interrupted byoptionally substituted heteroatoms. In particular, the D radical is aC₃- to C₆-alkylene bridge which is singly or doubly fused with phenyland/or naphthyl, and the phenyl or naphthyl group may bear 1, 2 or 3 ofthe aforementioned substituents.

[0073] The D radical together with the phosphorus atom and/or the oxygenatom(s) to which it is bonded is preferably a 5- to 8-memberedheterocycle in which D is a radical which is selected from the radicalsof the formulae II.1 to II.5,

[0074] where

[0075] T is O, S or NR^(i) where R^(i) is alkyl, cycloalkyl or aryl,

[0076] or T is a C₁- to C₃-alkylene bridge which may have a double bondand/or an alkyl, cycloalkyl or aryl substituent, and the arylsubstituent may bear 1, 2 or 3 of the substituents mentioned for aryl,

[0077] or T is a C₂- to C₃-alkylene bridge which is interrupted by O, Sor NR^(i),

[0078] R^(I), R^(II), R^(III), R^(IV), R^(V), R^(VI), R^(VII, R)^(VIII), R^(IX), R^(X), R^(XI) and R^(XII) are each independentlyhydrogen, alkyl, cycloalkyl, aryl, alkoxy, halogen, sulfonate, NE⁴E⁵,alkylene-NE⁴E⁵, trifluoromethyl, nitro, alkoxycarbonyl or cyano.

[0079] At least one of the ligands used in accordance with the inventionpreferably has a functional group which is capable of tautomerizing andof forming intermolecular noncovalent bonds. It is preferably selectedfrom groups of the formula

[0080] and the tautomers thereof where Y is O, S or NR⁴ where R⁴ ishydrogen, alkyl, cycloalkyl, heterocycloalkyl, aryl or hetaryl.

[0081] Factors on which the position of the particular tautomerizationequilibrium depends include the Y group and also the substituentscapable of tautomerizing. They are illustrated by way of examplehereinbelow for keto-enol tautomerization (especiallycarboxamide-imidocarboxylic acid tautomerization and amidinetautomerization):

[0082] The ligands used in accordance with the invention preferably haveat least one structural element of the general formulae I.a or I.b

[0083] or tautomers thereof where

[0084] R¹ and R² are each independently alkyl, alkoxy, cycloalkyl,cycloalkoxy, heterocycloalkyl, heterocycloalkoxy, aryl, aryloxy, hetarylor hetaryloxy,

[0085] R³ is hydrogen or is as defined for R¹ and R²,

[0086] X is a bivalent bridging group having from 1 to 5 bridging atomsbetween the flanking bonds,

[0087] Y is O, S or NR⁴ where R⁴ is hydrogen, alkyl, cycloalkyl,heterocycloalkyl, aryl or hetaryl,

[0088] and two or more than two of the X radicals and R¹ to R⁴ togetherwith the structural element of the formula I.a or I.b to which they arebonded may be a mono- or polycyclic compound.

[0089] With regard to suitable and preferred R¹ and R² radicals,reference is made to the preceding remarks.

[0090] The bivalent bridging X group preferably has from 1 to 4, morepreferably from 1 to 3, bridging atoms between the flanking bonds.

[0091] The bivalent bridging X group is preferably a C₁-C₅-alkylenebridge which, depending on the number of bridging atoms, may have one ortwo double bonds and/or one, two, three or four substituents which areselected from alkyl, cycloalkyl, heterocycloalkyl, aryl, hetaryl,carboxylate, sulfonate, phosphonate, NE¹E² (E¹, E²=hydrogen, alkyl,cycloalkyl, acyl or aryl), hydroxyl, thiol, halogen, nitro, acyl orcyano, and the cycloalkyl, aryl and hetaryl substituents mayadditionally bear one, two or three substituents which are selected fromalkyl, alkoxy, halogen, trifluoromethyl, nitro, alkoxycarbonyl andcyano, and/or one or two nonadjacent bridging atoms of theC₁-C₅-alkylene bridge X may be replaced by a heteroatom or aheteroatom-containing group, and/or the alkylene bridge X may be singlyor doubly fused with aryl and/or hetaryl, and the fused aryl and hetarylgroups may each bear one, two or three substituents which are selectedfrom alkyl, cycloalkyl, aryl, alkoxy, cycloalkoxy, aryloxy, acyl,halogen, trifluoromethyl, nitro, cyano, carboxyl, alkoxycarbonyl orNE¹E² (E¹ and E²=hydrogen, alkyl, cycloalkyl, acyl or aryl) and/or twoor more than two bridging atoms of the C₁-C₅-alkylene bridge X togetherwith the structural element of the formula I.a or I.b to which they arebonded may be a mono- or polycyclic compound.

[0092] X is preferably a C₁-C₅-alkylene bridge which may have one or twodouble bonds. In addition, two or more than two of the bridging atoms ofthe bridge X together with the structural element of the formula I.a orI.b to which they are bonded may preferably be a mono- or polycycliccompound.

[0093] The ligands used in accordance with the invention preferably haveat least one structural element of the general formulae I.a or I.b inwhich the X group and the R³ radical together with the —NH—C(═Y)— groupto which they are bonded are a 5- to 8-membered, preferably 6-memberedring. This ring may have one, two or three double bonds, and one ofthese double bonds may be based on a tautomeric —N═C(YH)— groupPreference is given to 6-membered rings which, taking into account thetautomerization, have three double bonds. Such ring systems in which oneof the tautomers may form an aromatic ring system are particularlystable. The rings mentioned may be unsubstituted or have one, two,three, four or five of the aformentioned substituents. These arepreferably selected from C₁-C₄-alkyl, more preferably methyl, ethyl,isopropyl or tert-butyl, C₁-C₄-alkoxy, especially methoxy, ethoxy,isopropyloxy or tert-butyloxy, and also aryl, preferably phenyl. In asuitable embodiment, the rings mentioned have at least one double bond,and the radicals bonded to this double bond are a fused ring systemhaving 1, 2 or 3 further rings. These are preferably benzene ornaphthalene rings. Fused benzene rings are preferably unsubstituted orhave 1, 2 or 3 substituents which are selected from alkyl, alkoxy,carboxylate, sulfonate, halogen, NE¹E², trifluoromethyl, nitro,alkoxycarbonyl, acyl and cyano. Fused naphthalene rings are preferablyunsubstituted or, in the nonfused and/or in the fused ring, each have 1,2 or 3 of the substituents mentioned above for the fused benzene rings.

[0094] The ligands used in accordance with the invention are preferablyselected from compounds of the general formulae I.1 to I.3

[0095] and the tautomers thereof where one of the R⁵ to R⁹ radicals is agroup of the formula

—W′—PR¹R² where

[0096] W′ is a single bond, a heteroatom, a heteroatom-containing groupor a bivalent bridging group having from 1 to 4 bridging atoms betweenthe flanking bonds,

[0097] R¹ and R² are each as defined above,

[0098] the R⁵ to R⁹ radicals which are not W′—PR¹R² are eachindependently hydrogen, alkyl, cycloalkyl, heterocycloalkyl, aryl,hetaryl, WCOOR^(o), WCOO⁻M⁺, W(SO₃)R^(o), W(SO₃)⁻M⁺, WPO₃(R^(o))(R^(p)),W(PO₃)²⁻(M⁺)₂, WNE¹E², W(NE¹E²E³)⁺X⁻, WOR^(q), WSR^(q),(CHR^(r)CH₂O)_(x)R^(q), (CH₂NE¹)_(x)R^(q), (CH₂CH₂NE¹)_(x)R^(q),halogen, nitro, acyl or cyano,

[0099]  where

[0100] W is a single bond, a heteroatom, a heteroatom-containing groupor a bivalent bridging group having from 1 to 20 bridging atoms,

[0101] R^(o) and R^(p) are each identical or different radicals selectedfrom alkyl, cycloalkyl, acyl or aryl,

[0102] R^(q), E¹, E², E³ are each identical or different radicalsselected from hydrogen, alkyl, cycloalkyl, acyl and aryl,

[0103] R^(r) is hydrogen, methyl or ethyl,

[0104] M⁺ is one cation equivalent,

[0105] X⁻ is one anion equivalent and

[0106] x is an integer from 1 to 240,

[0107] and in each case two adjacent R⁵, R⁶, R⁷, R⁸ and R⁹ radicals,together with the ring carbon atoms to which they are bonded, may alsobe a fused ring system having 1, 2 or 3 further rings, and

[0108] R^(a) and R^(b) are each hydrogen, alkyl, acyl, cycloalkyl,heterocycloalkyl, aryl or hetaryl.

[0109] In a suitable embodiment of the process according to theinvention, ligands of the general formulae I.1 to I.3 are used where R⁵and R⁶ and/or R⁷ and R⁸ are each a fused ring system having 1, 2 or 3further rings. When R⁵ and R⁶ and/or R⁷ and R⁸ are each a fused-on, i.e.fused, ring system, they are preferably benzene or naphthalene rings.Fused benzene rings are preferably unsubstituted and have 1, 2 or 3, inparticular 1 or 2, substituents which are preferably selected fromalkyl, alkoxy, halogen, SO₃H, sulfonate, NE¹E², alkylene-NE¹E²,trifluoromethyl, nitro, COOR^(o), alkoxycarbonyl, acyl and cyano. Fusednaphthalene rings are preferably unsubstituted or have, in the nonfusedring and/or in the fused ring, in each case 1, 2 or 3, in particular 1or 2, of the substituents specified above for the fused benzene rings.R⁷ and R⁸ are preferably each a fused-on ring system. In that case, R⁶and R⁹ are preferably each hydrogen, or one of these radicals ishydrogen and the other a substituent which is selected from C₁- toC₈-alkyl, preferably C₁- to C₄-alkyl, especially methyl, ethyl,isopropyl or tert-butyl.

[0110] In the compounds of the formulae I.1 to I.3, the R⁵ radical ispreferably a group of the formula —W′—PR¹R² as defined above.

[0111] In the groups of the formula —W′—PR¹R², W′ is preferably anoxygen atom or a single bond between the PR¹R² group and a ring carbonatom to which this group is bonded.

[0112] In the compounds of the formulae I.1 to I.3, the R¹ and R²radicals are preferably each independently C₁-C₈-alkyl such as methyl,ethyl, isopropyl and tert-butyl, C₅-C₈-cycloalkyl such as cyclohexyl, oraryl such as phenyl. The R¹ and R² radicals are preferably both aryl, inparticular both phenyl.

[0113] In the compounds I.1 to I.3, the R⁶, R⁷, R⁸ and R⁹ radicals arepreferably each independently selected from hydrogen, C₁-C₄-alkyl,C₁-C₄-alkoxy, carboxylate, sulfonate, NE¹E², halogen, trifluoromethyl,nitro, alkoxycarbonyl, acyl and cyano. R⁶, R⁷, R⁸ and R⁹ are preferablyeach hydrogen. Moreover, the R⁷ and R⁸ radicals, together with the ringcarbon atoms to which they are bonded, are preferably a fused-on ringsystem as defined above, in particular a benzene ring. In that case, theR⁶ and, where present, R⁹ radicals are preferably each hydrogen.

[0114] In the compound of the formula I.2, the R^(a) radical ispreferably hydrogen, C₁-C₈-alkyl such as methyl, ethyl, isopropyl andtert-butyl, acyl, C₅-C₈-cycloalkyl such as cyclohexyl, or C₆-C₁₀-arylsuch as phenyl. R^(a) is more preferably acyl, in particular alkanoylsuch as acetyl, propanoyl, butanoyl, isobutanoyl and pivaloyl.

[0115] In the compounds of the formula I.3, the R^(b) radical ispreferably hydrogen, C₁-C₈-alkyl such as methyl, ethyl, isopropyl andtert-butyl, C₅-C₈-cycloalkyl such as cyclohexyl, C₆-C₁₀-aryl such asphenyl, or hetaryl.

[0116] The compounds of the formulae I.1 to I.3 (as defined above anddetailed more precisely hereinbelow), irrespective of their capabilityof forming intermolecular noncovalent bonds, are also suitable asligands in hydroformylation catalysts. The invention therefore alsoprovides a process for hydroformylating compounds which contain at leastone ethylenically unsaturated double bond by reacting with carbonmonoxide and hydrogen in the presence of a catalyst comprising at leastone complex of a metal of transition group VIII of the Periodic Table ofthe Elements with ligands which are selected from compounds of thegeneral formulae I.1 to I.3.

[0117] The ligands used in accordance with the invention are preferablyselected from compounds of the general formulae I.i. to I.iii

[0118] and the tautomers thereof where

[0119] a is 0 or 1,

[0120] R¹ and R² are each as defined above,

[0121] R⁶ to R⁹ are each independently hydrogen, C₁-C₄-alkyl,C₁-C₄-alkoxy, acyl, aryl, heteroaryl, halogen, C₁-C₄-alkoxycarbonyl orcarboxylate,

[0122] and in each case two adjacent R⁶, R⁷, R⁸ and R⁹ radicals,together with the ring carbon atoms to which they are bonded, may alsobe a fused ring system having 1, 2 or 3 further rings, and

[0123] R^(a) and R^(b) are each hydrogen, alkyl, acyl, cycloalkyl oraryl.

[0124] In the compounds of the formulae I.i to I.iii, the R¹ andR²radicals are preferably each independently C₁-C₈-alkyl such as methyl,ethyl, isopropyl and tert-butyl, C₅-C₈-cycloalkyl such as cyclohexyl, oraryl such as phenyl. The R¹ and R² radicals are preferably both aryl, inparticular both phenyl.

[0125] The R⁶, R⁷, R⁸ and R⁹ radicals in the compounds I.i to I.iii arepreferably each independently selected from hydrogen, C₁-C₄-alkyl,C₁-C₄-alkoxy, carboxylate, sulfonate, NE¹E², halogen, trifluoromethyl,nitro, alkoxycarbonyl, acyl and cyano. R⁶, R⁷, R⁸ and R⁹ are preferablyeach hydrogen. Moreover, the R⁷ and R⁸ radicals, together with the ringcarbon atoms to which they are bonded, are preferably a fused-on ringsystem as defined above, in particular a benzene ring. In that case, R⁶and, where present, R⁹ are preferably each hydrogen.

[0126] In the compounds of the formula I.ii, the R^(a) radical ispreferably hydrogen, C₁-C₈-alkyl such as methyl, ethyl, isopropyl andtert-butyl, C₅-C₈-cycloalkyl such as cyclohexyl, or C₆-C₁₀-aryl such asphenyl. R^(a) is more preferably acyl, in particular alkanoyl such asacetyl, propanoyl, butanoyl, isobutanoyl and pivaloyl.

[0127] In the compounds of the formula I.iii, the R^(b) radical ispreferably hydrogen, C₁-C₈-alkyl such as methyl, ethyl, isopropyl andtert-butyl, C₅-C₈-cycloalkyl such as cyclohexyl, or C₆-C₁₀-aryl such asphenyl or hetaryl.

[0128] Some advantageous compounds are listed hereinbelow, alsoincluding their tautomers:

[0129] An example of a ligand which can be used particularlyadvantageously in accordance with the invention is6-diphenylphosphino-1-H-pyridin-2-one.

[0130] The aforementioned ligands of the formulae I.1 to I.3, especiallyof the formulae I.i to I.iii and more especially of the formulae (1) to(4) are suitable either as sole ligands, in which case homo-dimerformation is assumed, or in ligand combinations, in which case at leastpartial hetero-dimer formation is assumed. In the case of ligandcombinations, all ligands may be selected from ligands of the formulaeI.1 to I.3 and especially from ligands of the formulae I.i to I.iii,more especially (1) to (4). However, it is also possible to select onlyat least one of the ligands of a ligand combination from ligands of theformulae specified and combine it with at least one different ligand.Suitable for combination (as one component of a hetero-dimer) arepreferably ligands which are selected from compounds of the followingformula II

[0131] where

[0132] one of the R¹⁰ to R¹⁴ radicals is a group of the formula—W″—PR¹R², where

[0133] W″ is a single bond, a hetero atom, a hetero atom-containinggroup or a divalent bridging group having from 1 to 4 bridging atomsbetween the flanking bonds,

[0134] R¹ and R² are each independently alkyl, alkoxy, cycloalkyl,cycloalkoxy, heterocycloalkyl, heterocycloalkoxy, aryl, aryloxy, hetarylor hetaryloxy,

[0135] the R¹⁰ to R¹⁴ radicals which are not —W″—PR¹R² are eachindependently hydrogen, alkyl, cycloalkyl, heterocycloalkyl, aryl,hetaryl, WCOOR^(s), WCOO⁻M⁺, W(SO₃)R^(s), W(SO₃)⁻M⁺, WPO₃(R^(s))(R^(t)),W(PO₃)²⁻(M⁺)₂, WNE⁷E⁸, W(NE⁷E⁸E⁹)⁺X⁻, WOR^(u), WSR^(u),(CHR^(v)CH₂O)_(Z)R^(u), (CH₂NE⁷)_(Z)R^(u), (CH₂CH₂NE⁷)_(Z)R^(u),halogen, nitro, acyl or cyano,

[0136] where

[0137] W is a single bond, a hetero atom, a hetero atom-containing groupor a divalent bridging group having from 1 to 20 bridging atoms,

[0138] R^(s) and R^(t) are each identical or different radicals selectedfrom alkyl, cycloalkyl, acyl and aryl,

[0139] R^(u), E⁷, E⁸, E⁹ are each identical or different radicalsselected from hydrogen, alkyl, cycloalkyl, acyl and aryl,

[0140] R^(v) is hydrogen, methyl or ethyl,

[0141] M⁺ is one cation equivalent,

[0142] X⁻ is one anion equivalent and

[0143] z is an integer from 1 to 240,

[0144] and in each case two adjacent R¹⁰, R¹¹, R¹², R¹³ and R¹⁴radicals, together with the ring carbon atoms to which they are bonded,may also be a fused ring system having 1, 2 or 3 further rings.

[0145] In the compounds of the formula II, the R¹⁰ radical is preferablya group of the formula —W″—PR¹R² as defined above.

[0146] In the groups of the formula —W″—PR¹R², W″ is preferably anoxygen atom or a single bond between the PR¹R² group and a ring carbonatom to which this group is bonded.

[0147] In the compounds of the formula II, the R¹ and R² radicals arepreferably each independently C₁-C₈-alkyl such as methyl, ethyl,isopropyl and tert-butyl, C₅-C₈-cycloalkyl such as cyclohexyl, or arylsuch as phenyl. The R¹ and R² radicals are preferably both aryl, inparticular both phenyl.

[0148] In the compounds of the formula II, the R¹¹, R¹², R¹³ and R¹⁴radicals are preferably each independently selected from hydrogen,C₁-C₄-alkyl, C₁-C₄-alkoxy, carboxylate, sulfonate, NE¹E², halogen,trifluoromethyl, nitro, alkoxycarbonyl, acyl and cyano. R⁶, R⁷, R⁸ andR⁹ are preferably each hydrogen. Moreover, the R¹² and R¹³ radicals,together with the ring carbon atoms to which they are bonded, arepreferably a fused-on ring system as defined above, in particular abenzene ring. In that case, the R¹¹ and R¹⁴ radicals are preferably eachhydrogen.

[0149] A preferred compound of the formula II is2-(diphenylphosphino)pyridine.

[0150] For illustration, some preferred ligand/ligand pairs are listedhereinbelow: Ligand 1 Ligand 2 (5)

(6)

(7)

(8)

[0151] The ligands which can be used in accordance with the inventioncan be prepared by customary processes known to those skilled in theart.

[0152] In J. Org. Chem. 2000, 65, p. 6917-6921, M. Akazome et al.describe the synthesis of(2-oxo-1,2-dihydro-x-pyridyl)diphenylphosphines where x=3, 5 and 6 (3-,5- and 6-diphenylphosphino-2-pyridinones) by lithiating thecorresponding 2-benzoyloxy-x-bromopyridines, subsequently coupling withchlorodiphenylphosphine and finally detaching the benzoyl protectinggroup with trifluoroacetic acid. With regard to the preparation of the2-benzoyloxy-x-bromopyridines used as reactants, reference is made tothe process described by Y. Dycharme and J. D. Wüst in J. Org. Chem.1988, 53, p. 5787.

[0153] In J. Org. Chem. 1978, 43, p. 947-949, G. R. Newkome and D. C.Hager describe a process for preparing pyridyldiphenylphosphines byreacting lithium diphenylphosphite with halopyridines. Afterward,6-diphenylphosphinopyridinone is obtained from lithium diphenylphosphideand 6-chloro-2-methoxypyridine.

[0154] The aforementioned documents are fully incorporated by way ofreference.

[0155] A novel process for preparing phosphinopyridinones and/ortautomers thereof comprises the reaction of a pyridine compound whichbears a protected hydroxyl group and a nucleophilically displaceablegroup with a solution of a phosphine and of an alkali metal in liquidammonia to obtain at least one pyridine compound which bears a protectedhydroxyl group and a phosphino group, and the subsequent detachment ofthe protecting group of the hydroxyl group. This process does not formpart of the subject matter of the present application, but rather of theparallel German patent application 103 13 320.8, which is incorporatedherein by way of reference.

[0156] The present invention further provides a catalyst comprising atleast one complex of a metal of transition group VIII of the PeriodicTable of the Elements with ligands which each have a phosphorus groupand at least one functional group capable of forming intermolecularnoncovalent bonds, the complex having ligands dimerized viaintermolecular noncovalent bonds and the distance between the phosphorusatoms of the dimerized ligands being at most 5 Å. Reference is made toall of the preceding remarks on suitable and preferred ligands.

[0157] The invention further provides a catalyst comprising at least onecomplex of a metal of transition group VIII of the Periodic Table havingat least one ligand which is selected from the compounds of the generalformulae I.1 to I.3 as defined above. Reference is made to all of thepreceding remarks on suitable and preferred ligands I.1 to 1.3.

[0158] The inventive catalysts which are used in accordance with theinvention preferably have two or more than two of the above-describedcompounds as ligands. At least two of the ligands are preferably presentin dimerized form. In addition to the above-described ligands, they mayalso have at least one further ligand which is preferably selected fromhalides, amines, carboxylates, acetylacetonate, aryl- andalkylsulfonates, hydride, CO, olefins, dienes, cycloolefins, nitriles,N-containing heterocycles, aromatics and heteroaromatics, ethers, PF₃,phospholes, phosphabenzenes and also mono-, di- and multidentatephosphine, phosphinite, phosphonite, phosphoramidite and phosphiteligands.

[0159] The metal of transition group VIII is preferably cobalt,ruthenium, rhodium, palladium, platinum, osmium or iridium, and inparticular cobalt, rhodium, ruthenium and iridium.

[0160] In general, the particular catalysts or catalyst precursors used,under hydroformylation conditions, form catalytically active species ofthe general formula H_(x)M_(y)(CO)_(z)L_(q) where M is a metal oftransition group VIII, L is a phosphorus compound of the formula I andq, x, y, z are integers dependent upon the valency and type of the metaland also on the valency of the L ligand. z and q are preferably eachindependently a value of at least 1, for example 1, 2 or 3. The sum of zand q is preferably a value from 1 to 5. The complexes may, if desired,additionally have at least one of the above-described further ligands.There is reason to assume that the catalytically active species also hasdimerized ligands (pseudochelates).

[0161] In a preferred embodiment, the hydroformylation catalysts areprepared in situ, in the reactor used for the hydroformylation reaction.However, the catalysts according to the invention may, if desired, alsobe prepared separately and be isolated by customary processes. Toprepare the catalysts according to the invention in situ, for example,at least one ligand used in accordance with the invention, a compound ora complex of a metal of transition group VIII, optionally at least onefurther additional ligand and optionally an activator may be reacted inan inert solvent under the hydroformylation conditions.

[0162] Suitable rhodium compounds or complexes are, for example,rhodium(II) and rhodium(III) salts such as rhodium(III) chloride,rhodium(III) nitrate, rhodium(II) sulfate, potassium rhodium sulfate,rhodium(II) or rhodium(III) carboxylate, rhodium(II) and rhodium(III)acetate, rhodium(III) oxide, salts of rhodium(III) acid,trisammonium-hexachlororhodate(III), etc. Also suitable are rhodiumcomplexes such as rhodium biscarbonyl acetylacetonate,acetylacetonatobisethylenerhodium(I), etc. Preference is given to usingrhodium biscarbonyl acetylacetonate or rhodium acetate.

[0163] Likewise suitable are ruthenium salts or compounds. Suitableruthenium salts are, for example, ruthenium(III) chloride,ruthenium(IV), ruthenium(VI) or ruthenium(VIII) oxide, alkali metalsalts of ruthenium-oxygen acids such as K₂RuO₄ or KRuO₄, or complexes,for example RuHCl(CO)(PPh₃)₃. Also useful in the process according tothe invention are the metal carbonyls of ruthenium such as trisrutheniumdodecacarbonyl or hexaruthenium octadecacarbonyl, or mixed forms inwhich CO has been partly replaced by ligands of the formula PR₃ such asRu(CO)₃(PPh₃)₂.

[0164] Suitable cobalt compounds are, for example, cobalt(II) chloride,cobalt(II) sulfate, cobalt(II) carbonate, cobalt(II) nitrate, theiramine or hydrate complexes, cobalt carboxylates such as cobalt acetate,cobalt ethylhexanoate, cobalt naphthanoate, and also the cobalt caproatecomplex. The carbonyl complexes of cobalt such as dicobalt octacarbonyl,tetracobalt dodecacarbonyl and hexacobalt hexadecacarbonyl may also beused here.

[0165] The compounds of cobalt, rhodium, ruthenium and iridium whichhave been mentioned and are further suitable compounds are known inprinciple and adequately described in the literature, or may be preparedby those skilled in the art in a similar manner to the compounds alreadyknown.

[0166] Suitable activators are, for example, Brönsted acids, Lewisacids, for example BF₃, AlCl₃, ZnCl₂, and Lewis bases.

[0167] The solvents are preferably the aldehydes which are formed in thehydroformylation of the particular olefins, and also theirhigher-boiling subsequent reaction products, for example the products ofthe aldol condensation. Solvents which are likewise suitable arearomatics such as toluene and xylenes, hydrocarbons or mixtures ofhydrocarbons, also for diluting the abovementioned aldehydes and thesubsequent products of the aldehydes. Further solvents are esters ofaliphatic carboxylic acids with alkanols, for example ethyl acetate orTexanol™, ethers such as tert-butyl methyl ether and tetrahydrofuran.

[0168] It is also possible to carry out the reactions in water oraqueous solvent systems which, in addition to water, contain awater-miscible solvent, for example a ketone such as acetone and methylethyl ketone or another solvent. For this purpose, ligands are usedwhich have been modified with polar groups, for example ionic groupssuch as SO₃ ⁻M⁺, CO₂ ⁻M⁺ where M⁺=Na⁺, K⁺ or NH₄ ⁺, or such as N(CH₃)₄⁺. The reactions are then effected in a biphasic catalysis, in which thecatalyst is in the aqueous phase and feedstocks and products form theorganic phase. The reaction may also be configured as a biphasiccatalysis in ionic liquids.

[0169] The molar ratio of monophosphorus ligands to metal of transitiongroup VIII is generally in the range from about 1:1 to 1000:1,preferably from 2:1 to 500:1.

[0170] Useful substrates for the hydroformylation process according tothe invention are in principle all compounds which contain one or moreethylenically unsaturated double bonds. These include, for example,olefins such as α-olefins, internal straight-chain and internal branchedolefins. Preference is given to using α-olefins, for example ethylene,propene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene,1-decene, 1-undecene, 1-dodecene, etc.

[0171] Suitable branched, internal olefins are preferably C₄-C₂₀-olefinssuch as 2-methyl-2-butene, 2-methyl-2-pentene, 3-methyl-2-pentene,branched, internal heptene mixtures, branched, internal octene mixtures,branched, internal nonene mixtures, branched, internal decene mixtures,branched, internal undecene mixtures, branched, internal dodecenemixtures, etc.

[0172] Suitable olefins to be hydroformylated are alsoC₅-C₈-cycloalkenes such as cyclopentene, cyclohexene, cycloheptene,cyclooctene and derivatives thereof, for example their C₁-C₂₀-alkylderivatives having from 1 to 5 alkyl substituents. Suitable olefins tobe hydroformylated are also vinylaromatics such as styrene,α-methylstyrene, 4-isobutylstyrene, etc. Suitable olefins to behydroformylated are also α,β-ethylenically unsaturated mono- and/ordicarboxylic acids, their esters, monoesters and amides, such as acrylicacid, methacrylic acid, maleic acid, fumaric acid, crotonic acid,itaconic acid, methyl 3-pentenoate, methyl 4-pentenoate, methyl oleate,methyl acrylate, methyl methacrylate, unsaturated nitriles such as3-pentenenitrile, 4-pentenenitrile, acrylonitrile, vinyl ethers such asvinyl methyl ether, vinyl ethyl ether, vinyl propyl ether, etc.,C₁-C₂₀-alkenols, -alkenediols and -alkadienols such as 2,7-octadienol-1.Suitable substrates are also di- or polyenes having isolated orconjugated double bonds. These include, for example, 1,3-butadiene,1,4-pentadiene, 1,5-hexadiene, 1,6-heptadiene, 1,7-octadiene,1,8-nonadiene, 1,9-decadiene, 1,1 0-undecadiene, 1,11-dodecadiene,1,12-tridecadiene, 1,13-tetradecadiene, vinylcyclohexene,dicyclopentadiene, 1,5,9-cyclooctatriene and also butadiene homo- andcopolymers.

[0173] In a suitable embodiment, the unsaturated compound used forhydroformylation is selected from internal linear olefins and olefinmixtures which contain at least one internal linear olefin. Suitablelinear (straight-chain) internal olefins are preferably C₄-C₂₀-olefinssuch as 2-butene, 2-pentene, 2-hexene, 3-hexene, 2-heptene, 3-heptene,2-octene, 3-octene, 4-octene, etc., and mixtures thereof.

[0174] The inventive catalysts which are used in accordance with theinvention are also advantageously suitable for hydroformylatingfunctionalized olefins, in particular functionalized 1-olefins. Theolefins to be hydroformylated are preferably selected from compounds ofthe general formula III

CH₂═CH—Z—(Fu)_(n)  (III)

[0175] where

[0176] Z is a bivalent bridging group having from 1 to 20 bridging atomsbetween the flanking bonds and

[0177] Fu is a functional group, and

[0178] n is an integer from 1 to 4.

[0179] The bivalent bridging group Z is preferably a C₁-C₂₀-alkylenebridge which, depending on the number of bridging atoms, may have one,two, three or four double bonds and/or one, two, three or foursubstituents, and the cycloalkyl, aryl and heteraryl substituents may inturn additionally bear one, two or three substituents which are selectedfrom alkyl, alkoxy, halogen, trifluoromethyl, nitro, alkoxycarbonyl andcyano, and/or from 1 to 10 nonadjacent bridging atoms of theC₁-C₂₀-alkylene bridge Z may be replaced by a heteroatom or aheteroatom-containing group, and/or the alkylene bridge Z may be singlyor doubly fused with aryl and/or hetaryl, in which case the fused aryland hetaryl groups may bear one, two or three substituents which areselected from alkyl, cycloalkyl, aryl, alkoxy, cycloalkoxy, aryloxy,acyl, halogen, trifluoromethyl, nitro, cyano, carboxyl, alkoxycarbonylor NE¹E² (E¹ and E²=hydrogen, alkyl, cycloalkyl, acyl or aryl).

[0180] The functional group Fu is preferably selected from —OH, —SH,—Cl, —Br, —COOR¹⁵, —O—C(═O)R¹⁶, —O—C(═O)—OR¹⁵, —O—C(═)—NR¹⁶R¹⁷,—NR¹⁷—C(═O)—R¹⁶, —NR¹⁷—C(═)—OR¹⁵, —NR¹⁶—C(═O)—NR¹⁷R¹⁸,

[0181] where

[0182] R¹⁵ is alkyl, cycloalkyl, heterocycloalkyl, aryl or hetaryl

[0183] R¹⁶, R¹⁷ and R¹⁸ are each independently hydrogen, alkyl,cycloalkyl, heterocycloalkyl, aryl or hetaryl.

[0184] Merely for illustration, some suitable functionalized olefins arelisted hereinbelow:

[0185] In the hydroformylation process according to the invention,preference is given to using an olefin mixture which is obtainable onthe industrial scale and in particular contains at least one internalolefin. These include, for example, the Ziegler olefins obtained byselective ethene oligomerization in the presence of alkylaluminumcatalysts. These are substantially unbranched olefins having a terminaldouble bond and an even number of carbon atoms. These also includeolefins obtained by ethene oligomerization in the presence of differentcatalyst systems, for example the predominantly linear α-olefinsobtained in the presence of alkylaluminum chloride/titaniumtetrachloride catalysts and the α-olefins obtained in the presence ofnickel-phosphine complex catalysts by the Shell Higher Olefin Process(SHOP). Suitable industrially available olefin mixtures are alsoobtained in the paraffin dehydrogenation of appropriate crude oilfractions, for example what are known as petroleum or diesel oilfractions. For the conversion of paraffins, predominantly of n-paraffinsto olefins, essentially three processes are used:

[0186] thermal cracking (steam cracking),

[0187] catalytically dehydrogenating and

[0188] chemically dehydrogenating by chlorinating anddehydrochlorinating.

[0189] Thermal cracking leads predominantly to α-olefins, while theother variants result in olefin mixtures which generally also haverelatively large proportions of olefins having internal double bonds.Suitable olefin mixtures are also the olefins obtained in the metathesisand telomerization reactions. These include, for example, the olefinsfrom the Phillips triolefin process, a modified SHOP process composed ofethylene oligomerization, double bond isomerization and subsequentmetathesis (ethenolysis).

[0190] Suitable technical olefin mixtures which can be used in thehydroformylation process according to the invention are also selectedfrom dibutenes, tributenes, tetrabutenes, dipropenes, tripropenes,tetrapropenes, mixtures of butene isomers, in particular raffinate II,dimeric butenes, dihexenes, dimers and oligomers from the Dimersol®process from IFP, Octol process® from Hüls, Polygas process, etc.

[0191] Preference is given to a process, wherein the hydroformylationcatalyst is prepared in situ by reacting at least one ligand which canbe used in accordance with the invention, a compound or a complex of ametal of transition group VIII and optionally an activator in an inertsolvent under the hydroformylation conditions.

[0192] The hydroformylation reaction may be effected continuously,semicontinuously or batchwise.

[0193] Suitable reactors for the continuous reaction are known to thoseskilled in the art and are described, for example, in UllmannsEnzyklopädie der technischen Chemie, vol. 1, 3rd ed., 1951, p. 743 ff.

[0194] Suitable pressure-rated reactors are likewise known to thoseskilled in the art and are described, for example in UllmannsEnzyklopädie der technischen Chemie, vol. 1, 3rd ed., 1951, p. 769 ff.In general, an autoclave is used for the process according to theinvention and may, if desired, be provided with a stirrer apparatus andan internal lining.

[0195] The composition of the synthesis gas which is used in the processaccording to the invention and is composed of carbon monoxide andhydrogen may vary within wide ranges. The molar ratio of carbon monoxideto hydrogen is generally from about 5:95 to 70:30, preferably from about40:60 to 60:40. Particular preference is given to using a molar ratio ofcarbon monoxide to hydrogen in the range of about 1:1.

[0196] The temperature in the hydroformylation reaction is generally inthe range of from about 20 to 180° C., preferably from about 50 to 150°C. In general, the pressure is in the range from about 1 to 700 bar,preferably from 1 to 600 bar, in particular from 1 to 300 bar. Dependingon the activity of the hydroformylation catalyst according to theinvention used, the reaction pressure may be varied. In general, thecatalysts according to the invention based on phosphorus compoundspermit reaction in the range of low pressures, for instance in the rangefrom 1 to 100 bar.

[0197] The inventive hydroformylation catalysts used in accordance withthe invention can be removed from via effluent of the hydroformylationreaction by processes known to those skilled in the art and maygenerally be reused for the hydroformylation.

[0198] The above-described catalysts may also be immobilized in asuitable manner, for example by binding via functional groups suitableas anchor groups, adsorption, grafting, etc., on a suitable support, forexample on glass, silica gel, synthetic resins, polymers, etc. They arethen also suitable for use as solid phase catalysts.

[0199] The hydroformylation activity of catalysts based on theabove-described ligands is surprisingly generally higher than theisomerization activity with respect to the formation of internal doublebonds. Advantageously, the inventive catalysts used in accordance withthe invention have a high selectivity in favor of the α-aldehydes or-alcohols in the hydroformylation of α-olefins. In addition, thecatalysts according to the invention are also suitable forhydroformylating a multitude of substituted olefins which are otherwisenot readily amenable to hydroformylation. In addition, the catalystsgenerally have high stability under the hydroformylation conditions, sothat they can generally be used to achieve longer catalyst on-streamtimes than the prior art catalysts based on conventional chelateligands. Advantageously, the inventive catalysts used in accordance withthe invention also have high activity, so that the correspondingaldehydes or alcohols can generally be obtained in good yields. In thehydroformylation of α-olefins and also of internal, linear olefins, theyadditionally exhibit very low selectivity for the hydrogenation productof the olefin used.

[0200] The invention further provides a process for preparing2-propylheptanol, by

[0201] a) hydroformylating butene or a butene-containing C₄-hydrocarbonmixture in the presence of a catalyst as defined above with carbonmonoxide and hydrogen to obtain an n-valeraldehyde-containinghydroformylation product,

[0202] b) optionally subjecting the hydroformylation product to aseparation to obtain an n-valeraldehyde-enriched fraction,

[0203] c) subjecting the hydroformylation product obtained in step a) orthe n-valeraldehyde-enriched fraction obtained in step b) to an aldolcondensation,

[0204] d) catalytically hydrogenating the products of the aldolcondensation with hydrogen to give alcohols, and

[0205] e) optionally subjecting the hydrogenation products to aseparation to obtain a 2-propylheptanol-enriched fraction.

[0206] a) Hydroformylation

[0207] Suitable starting materials for the hydroformylation are bothsubstantially pure 1-butene and mixtures of 1-butene with 2-butene andindustrially available C₄ hydrocarbon streams which comprise 1-buteneand/or 2-butene. Preference is given to C₄ cuts which are available inlarge amounts from FCC plants and steam crackers. These consistsubstantially of a mixture of the isomeric butenes and butane.

[0208] C₄ hydrocarbon streams suitable as a starting material contain,for example, from 50 to 99 mol %, preferably from 60 to 90 mol %, ofbutenes, and from 1 to 50 mol %, preferably from 10 to 40 mol %, ofbutanes. The butene fraction preferably includes from 40 to 60 mol % of1-butene, from 20 to 30 mol % of 2-butene and less than 5 mol %, inparticular less than 3 mol %, of isobutene (based on the butenefraction). A particularly preferred feedstock which is used is what isknown as raffinate II , which is an isobutene-depleted C₄ cut from anFCC plant or a steam cracker.

[0209] Hydroformylation catalysts based on the phosphorus chelatecompounds used in accordance with the invention as ligandsadvantageously have high n-selectivity, even when 2-butene and 2-butenichydrocarbon mixtures are used as the starting material. This also allowssuch feedstocks to be used economically in the process according to theinvention, since the desired n-valeraldehyde results in good yields.

[0210] b) Separation

[0211] In a suitable process variant, the product-enriched fractionobtained in step a) after the catalyst system has been removed issubjected to a further separation to obtain an n-valeraldehyde-enrichedfraction. The hydroformylation product is separated into ann-valeraldehyde-enriched fraction and an n-valeraldehyde-depletedfraction by customary processes known to those skilled in the art.Preference is given to distillation using known separating apparatussuch as distillation columns, for example tray columns, which may, ifdesired, be equipped with bubble-caps, sieve plates, sieve trays,valves, etc., evaporators such as thin-film evaporators, falling-filmevaporators, wiped-blade evaporators, etc.

[0212] c) Aldol condensation

[0213] Two molecules of C₅-aldehyde may be condensed to giveα,β-unsaturated C₁₀-aldehydes. The aldol condensation is effected in amanner known per se, for example by the action of an aqueous base suchas sodium hydroxide solution or potassium hydroxide solution.Alternatively, a heterogeneous basic catalyst such as magnesium oxideand/or aluminum oxide may be used (cf., for example, EP-A 792 862). Thecondensation of two molecules of n-valeraldehyde results in2-propyl-2-heptenal. When the hydroformylation product obtained in stepa) or after the separation in step b) also comprises furtherC₅-aldehydes such as 2-methylbutanal and in some cases2,2-dimethylpropanal, these likewise undergo an aldol condensation,resulting in the condensation products of all possible aldehydecombinations, for example 2-propyl-4-methyl-2-hexenal. A proportion ofthese condensation products, for example of up to 30% by weight, doesnot prevent advantageous further processing to2-propylheptanol-containing C₁₀-alcohol mixtures which are suitable asplasticizer alcohols.

[0214] d) Hydrogenation

[0215] The products of the aldol condensation may be catalyticallyhydrogenated with hydrogen to C₁₀-alcohols, in particular2-propylheptanol.

[0216] For the hydrogenation of the C₁₀-aldehydes to the C₁₀-alcohols,the catalysts of the hydroformylation are in principle usually alsosuitable at relatively high temperatures; however, preference isgenerally given to more selective hydrogenation catalysts which are usedin a separate hydrogenation stage. Suitable hydrogenation catalysts aregenerally transition metals, for example, Cr, Mo, W, Fe, Rh, Co, Ni, Pd,Pt, Ru etc., or mixtures thereof, which may be applied to supports, forexample activated carbon, aluminum oxide, kieselguhr, etc., to increasethe activity and stability. To increase the catalytic activity, Fe, Coand preferably Ni, also in the form of the Raney catalysts, may be usedas metal sponge having a very large surface area. Depending on theactivity of the catalyst, the C₁₀-aldehydes are hydrogenated preferablyat elevated temperatures and elevated pressure. The hydrogenationtemperature is preferably from about 80 to 250° C.; the pressure ispreferably from about 50 to 350 bar.

[0217] The crude hydrogenation product may be worked up to give theC₁₀-alcohols by customary processes, for example by distillation.

[0218] e) Separation

[0219] If desired, the hydrogenation products may be subjected to afurther separation to obtain a 2-propylheptanol-enriched fraction and a2-propylheptanol-depleted fraction. This separation may be effected bycustomary processes known to those skilled in the art, for example bydistillation.

[0220] Hydroformylation catalysts which comprise a complex of at leastone metal of transition group VIII of the Periodic Table with a ligandwhich can be used in accordance with the invention are advantageouslysuitable for use in a process for preparing 2-propylheptanol. Thecatalysts have high n-selectivity, so that a good yield ofn-valeraldehyde is obtained when either substantially pure 1-butene isused or when 1-butenic/2-butenic hydrocarbon mixtures are used, forexample C₄ cuts.

[0221] The invention further provides the use of catalysts comprising atleast one complex of a metal of transition group VIII with at least oneligand as described above for hydroformylating, carbonylating and forhydrogenating.

[0222] The invention is illustrated in detail with the aid of thenonlimiting examples which follow.

EXAMPLE A Calculation of 6-diphenylphosphinopyridinone Dimers (6-DPPonDimers) to Forecast Their Pseudochelate Properties

[0223] With the aid of a graphic molecular modeling program, allpossible hydrogen-bonded dimers of 6-DPPon and its tautomers aregenerated. These dimer structures are then optimized by quantumchemistry methods.

[0224] 6-DPPon ligands are only suitable as chelate ligands when theseparation of the phosphorus atoms in the calculated dimer structure isless than 5 Å.

[0225] The calculated dimer formation of 6-diphenylphosphinopyridone isshown hereinbelow. The calculation shows that the interaction of a6-diphenylphosphinopyrid-2-one with2-hydroxy-6-diphenylphosphinopyridine (a tautomer of6-diphenylphosphinopyrid-2-one) leads to an arrangement in which thephosphorus atoms have a separation of 3.8 Å (Method: DFT, B3-LYP, basis:TZVP (A. Schäfer et al., J. Chem. Phys. (1994), 100, p. 5829 ff)). Thesystem is thus capable of chelating and of its known associatedadvantages.

EXAMPLE B Crystal Structure Analysis of [cis-PtCl₂(6-DPPon)₂]

[0226] In a Schlenk tube, 68.4 mg (182 μmol, 1 eq) of [cis-PtCl₂(COD)₂]were dissolved in 2.5 ml of CH₂Cl₂ and admixed with 102 mg (366 μmol, 2eq) of 6-diphenylphosphino-1H-pyridin-2-one. The lemon-yellow suspensionwas admixed with a further 2.5 ml of CH₂Cl₂ and the resulting paleyellow solution stirred at room temperature for 5 min. After the solventhad been removed under high vacuum (HV), the remaining residue wassuspended twice in 5 ml each time of pentane, the supernatant solventwas pipetted off and the white solid was dried under HV. Suitablecrystals for a crystal structure analysis were obtained from a solutionof 20 mg of [cis-PtCl₂(6-DPPon)₂] in 1 ml of CH₂Cl₂. FIG. 1 shows aball-and-stick diagram of the structure determined. TABLE 1 Data of theX-ray structural analysis Empirical formula C₃₅ H₃₀ Cl₄ N₂ O₂ P₂ PtMolar mass 909.44 Temperature 100(2) K Wavelength 0.71073 A Crystalsystem, space group Monoclinic, P 21/a Lattice constants a = 16.8292(3)Å alpha = 90° b = 11.1616(2) Å beta = 101.7809(11)° c = 18.6043(3) Ågamma = 90° Volume 3421.03(10) Å³ Z, density (calculated) 4, 1.766Mg/m{circumflex over ( )}3 Absorption coefficient 4.543 mm⁻¹ F(000) 1784Crystal size 0.43 × 0.3 × 0.25 mm Theta range measured 2.89 to 27.50°Index limits −21<=h<=21, −14<=k<=14, −14<= l<=24 Measured/independentreflections 19764/7783 [R(int) = 0.0313] Absorption correctionsemiempirical Max. and min. transmission 0.294 and 0.249 Structurerefining least squares against F² Data/restraints/parameters 7783/0/423Goodness-of-fit on F{circumflex over ( )}2 1.059 R values [l>2σ(l)] R1 =0.0205, wR2 = 0.0478 R values (all data) R1 = 0.0250, wR2 = 0.0496Max/min residual electron density 0.926 and −1.475 e Å³

[0227] TABLE 2 Atom coordination and thermal parameters x Y z U(eq)C(11) 4628(1) 111(2) 8359(1) 18(1) C(12) 4100(2) 888(3) 8588(2) 26(1)C(13) 3794(2) 560(3) 9208(2) 33(1) C(14) 4037(2) −494(3) 9555(2) 32(1)C(15) 4595(2) −1211(3) 9295(2) 26(1) C(21) 4594(1) 1660(2) 7075(1) 16(1)C(22) 4806(2) 2766(2) 7407(2) 22(1) C(23) 4465(2) 3813(2) 7085(2) 26(1)C(24) 3904(2) 3760(2) 6423(2) 24(1) C(25) 3693(2) 2670(2) 6086(1) 25(1)C(26) 4034(2) 1620(2) 6407(1) 21(1) C(31) 6094(1) 725(2) 7866(1) 15(1)C(32) 6480(1) 508(2) 8588(1) 19(1) C(33) 7287(2) 843(2) 8839(2) 24(1)C(34) 7715(2) 1378(2) 8362(2) 26(1) C(35) 7335(2) 1603(2) 7640(2) 24(1)C(36) 6522(2) 1294(2) 7392(1) 18(1) C(41) 6646(1) −1924(2) 7649(1) 15(1)C(42) 7460(2) −1791(2) 7753(1) 20(1) C(43) 7936(2) −1990(3) 8466(2)25(1) C(44) 7582(2) −2311(2) 9033(2) 26(1) C(45) 6727(2) −2440(2)8939(1) 22(1) C(51) 6061(1) −3465(2) 6465(1) 16(1) C(52) 5880(2)−3750(2) 5718(1) 21(1) C(53) 5961(2) −4912(3) 5485(2) 25(1) C(54)6225(2) −5805(3) 5993(2) 29(1) C(55) 6406(2) −5537(2) 6738(2) 28(1)C(56) 6323(2) −4371(2) 6975(1) 21(1) C(61) 6332(1) −1021(2) 6108(1)15(1) C(62) 7058(1) −1329(2) 5893(1) 17(1) C(63) 7324(2) −632(2) 5367(1)21(1) C(64) 6881(2) 347(3) 5053(1) 23(1) C(65) 6156(2) 641(2) 5256(1)22(1) C(66) 5878(2) −51(2) 5776(1) 18(1) Cl(1) 3356(1) −935(1) 6987(1)18(1) Cl(2) 4147(1) −3078(1) 6206(1) 23(1) N(1) 4880(1) −936(2) 8699(1)20(1) N(2) 6299(1) −2243(2) 8233(1) 18(1) O(1) 4857(1) −2226(2) 9650(1)33(1) O(2) 6354(1) −2710(2) 9439(1) 29(1) P(1) 5031(1) 300(1) 7523(1)14(1) P(2) 5933(1) −1935(1) 6759(1) 12(1) Pt(1) 4685(1) −1396(1) 6874(1)12(1) C(500) 5866(2) −5480(3) 9494(2) 32(1) Cl(51) 4907(1) −5174(1)8943(1) 47(1) Cl(52) 6558(1) −5969(1) 8958(1) 50(1)

EXAMPLES 1-8 (INVENTIVE) Low Pressure Hydroformylations of 1-octene

[0228] The hydroformylation was carried out in parallel in 8 autoclavesof identical design. To this end, in a Schlenk tube, 1.8 mg (7.0 μmol)of rhodium dicarbonyl acetylacetonate were dissolved in 24 ml of tolueneand admixed with 39 mg (0.14 mmol) of6-phenylphosphino-1H-pyridin-2-one. The resulting solution was dividedequally between the 8 autoclaves and then conditioned by stirring at 90°C. and under 5 bar of synthesis gas (CO/H=1:1) for 30 minutes. Thetemperature for the individual autoclaves was then adjusted as specifiedin table 3 and the pressure for all autoclaves was increased uniformlyto 10 bar of CO/H₂ (1:1). Under these conditions, 0.69 g (6.2 mmol) of1-octene per autoclave was added via a lock and each lock wassubsequently flushed with 0.5 ml of toluene. Pressure and temperaturewere kept constant over the entire reaction time. After 4 hours ofreaction time, the autoclaves were cooled, decompressed and emptied. Theresulting reaction solutions were analyzed by gas chromatography (GC).The results obtained are reproduced in table 3. TABLE 3 Hydroformylationof 1-octene at 10 bar of CO/H₂ and different temperatures Total Tem-1-Octene nonanals n-fraction^([a]) α-fraction^([b]) Exam- perature(conversion) (yield) (selectivity) (selectivity) ple [° C.] [%] [%] [%][%] 1 40 3 2 93 100 2 50 10 9 95 100 3 65 56 53 97 100 4 80 95 85 96 1005 95 98 85 96 100 6 110 96 82 93 100 7 125 90 71 89 100 8 140 81 34 83100

COMPARATIVE EXAMPLES 1-8 Low Pressure Hydroformylations of 1-octene

[0229] In a similar manner to examples 1-8, the hydroformylation wascarried out in parallel in 8 autoclaves of identical design. To thisend, in a Schlenk tube, 1.8 mg (7.0 μmol) of rhodium dicarbonylacetylacetonate were dissolved in 24 ml of toluene and admixed with 37mg (0.14 mmol) of triphenylphosphine. The resulting solution was dividedequally between the 8 autoclaves and then conditioned by stirring at 90°C. and under bar of synthesis gas (CO/H₂=1:1) for 30 minutes. Thetemperature for the individual autoclaves was then adjusted as specifiedin table 4 and the pressure for all autoclaves was increased uniformlyto 10 bar of CO/H₂ (1:1). Under these conditions, 0.69 g (6.2 mmol) of1-octene per autoclave was added via a lock and each lock wassubsequently flushed with 0.5 ml of toluene. Pressure and temperaturewere kept constant over the entire reaction time. After 4 hours ofreaction time, the autoclaves were cooled, decompressed and emptied. Theresulting reaction solutions were analyzed by gas chromatography (GC).The results obtained are reproduced in table 4. TABLE 4 Hydroformylationof 1-octene with rhodium/triphenylphosphine as a catalyst at 10 bar ofCO/H₂ and different temperatures Tem- 1-Octene Total pera- (con-nonanals n-fraction^([a]) α-fraction^([b]) Comparative ture version)(yield) (selectivity) (selectivity) example [° C.] [%] [%] [%] [%] 1 4016 4 77 100 2 50 17 6 76 100 3 65 22 22 72 100 4 80 98 89 73 100 5 95 9884 70 98 6 110 99 67 61 94 7 125 97 44 56 93 8 140 94 12 62 97

[0230] General Experimental Description for Carrying Out BatchwiseHydroformylation Experiments (Examples 9-11)

[0231] Rhodium precursor, ligand and solvent were mixed in a Schlenktube under nitrogen inert gas. The resulting solution was transferred toa 70 ml of 100 ml autoclave flushed with CO/H₂ (1:1). 5 bar of CO/H₂(1:1) were injected at room temperature. Under vigorous stirring with asparging stirrer, the reaction mixture was heated to the desiredtemperature within 30 minutes. A lock was then used to inject the olefinused into the autoclave using elevated CO/H₂ pressure. The desiredreaction pressure was then set immediately by injecting CO/H₂ (1:1).During the reaction, the pressure was kept constant in the reactor usinga pressure regulator. After the reaction time, the autoclave was cooled,decompressed and emptied. The reaction mixture was analyzed by means ofgas chromatography.

EXAMPLE 9 Low Pressure Hydroformylation of 1-octene

[0232] Starting from 7.4 mg (29 μmol) of rhodium dicarbonylacetylacetonate, 162 mg (0.58 mmol) of6-diphenylphosphino-1H-pyridin-2-one, 25.6 g (228 mmol) of 1-octene and25 g toluene, a 1-octene conversion of 100% was obtained in accordancewith the general experimental procedure at 100° C. and 10 bar of CO/H₂after 3 hours of reaction time. The yield of nonanals was 91%, theselectivity for n-nonanal (n-fraction) was 97% and the selectivity forn-nonanal and 2-methyloctanal (α-fraction) was 100%.

EXAMPLE 10 Low Pressure Hydroformylation of 2-octene

[0233] Starting from 7.3 mg (28 μmol) of rhodium dicarbonylacetylacetonate, 162 mg (0.58 mmol) of6-diphenylphosphino-1H-pyridin-2-one, 25.4 g (226 mmol) of 2-octene(cis:trans ratio=80:20) and 25 g toluene, a 2-octene conversion of 100%was obtained in accordance with the general experimental procedure at90° C. and 10 bar of CO/H₂ after 3 hours of reaction time. The yield ofnonanals was 95%, the selectivity for n-nonanal (n-fraction) was 5% andthe selectivity for n-nonanal and 2-methyloctanal (α-fraction) was 57%.

EXAMPLE 11 Low Pressure Hydroformylation of 1-butene

[0234] Starting from 1.9 mg (7.4 μmol) of rhodium dicarbonylacetylacetonate, 39 mg (0.14 mmol) of6-diphenylphosphino-1H-pyridin-2-one, 6.5 g (37 mmol of 1-butene) of amixture of 32% of 1-butene and 68% of isobutane, and 6.0 g of toluene, a1-butene conversion of 100% was achieved in accordance with the generalexperimental procedure at 90° C. and total pressure 16 bar after areaction time of 4 hours. The yield of aldehydes was 100% and theselectivity for n-valeraldehyde (n-fraction) 97%.

EXAMPLE 12

[0235] Hydroformylation of Functionalized Olefins According to Table 5Using 6-diphenylphosphino-1 H-pyridin-2-one (6-DPPon) as a Ligand

[0236] 1.8 mg (6.98 μmol, 1 eq) of [Rh(CO)₂acac] were dissolved in 10 mlof toluene and admixed with 39.1 mg (0.14 mmol, 20 eq) of6-diphenylphosphinopyridone. The orange-colored solution was stirred for5 min and then admixed with 6.98 mmol (1000 eq) of the particularsubstrate. The solution was transferred to the autoclave, 10 bar ofCO/H₂ (1:1) were injected and the autoclave was heated to 70° C. After20 h, the reaction was stopped by cooling to room temperature anddecompressing the autoclave. The solution was filtered through a littlesilica gel together with approx. 50 ml of ethyl acetate and concentratedunder reduced pressure. The crude products were analyzed by means of ¹Hand ¹³C NMR spectroscopy.

5 COMPARATIVE EXAMPLE 13 Hydroformylation of the Substrates inAccordance with Table 5 Using Triphenylphosphine as a Ligand

[0237] 1.8 mg (6.98 μmol, 1 eq) of [Rh(CO)₂acac] (acac=acetylacetonate)were dissolved in 10 ml of toluene and admixed with 36.9 mg (0.14 mmol,20 eq) of triphenylphosphine. The pale yellow solution was stirred for 5min and then admixed with 6.98 mmol (1 000 eq) of the particularsubstrate. The solution was transferred to the autoclave, 10 bar ofCO/H₂ (1:1) were injected and the autoclave was heated to 70° C. After20 h, the reaction was stopped by cooling to room temperature anddecompressing the autoclave. The solution was filtered through a littlesilica gel together with approx. 50 ml of ethyl acetate and concentratedunder reduced pressure. The crude products were analyzed by means of ¹Hand ¹³C NMR spectroscopy. TABLE 5^([1]) 6-DPPon TPP Substrate linearbranched conversion linear branched conversion

95.4 4.6 >99%^([2],[3]) 89.6 10.4 >99%^([2],[3])

89.0 11.0 >99%^([3]) 74.1 25.9 >99%^([3])

96.0 4.0 >99% 77.0 23.0 >99%

83.0 17.0 >99% 77.2 22.8 >99%

80.6 19.4 >99% — — —

96.2 3.8 >99% 71.1 28.9 >99%

86.5 13.5 >99% 61.6 38.4 >99%

95.8 4.2 >99% 69.0 31.0 >99%

97.0 3.0 >99% 74.0 26.0 >99%

97.0 3.0 >99% 72.0 28.0 not determined

[0238] When the formation of noncovalent bonds between the ligands isdisrupted by adding acetic acid and methanol, the n-selectivity reducesat otherwise still good conversions.

EXAMPLE 14 Preparation of 6-(diphenylphosphino)-2-pivaloylaminopyridine[6-DPPAP]

[0239] 14.1 Preparation of 6-bromo-2-aminopyridine

[0240] In a steel autoclave having a glass insert, 10.00 g of2,6-dibromopyridine (42.2 mmol) were suspended in 50 ml of concentratedaqueous ammonia. The autoclave was closed and heated to 190° C. for 6 hin a heating mantle (pressurized to approx. 25 bar). After the coolingand decompression of the autoclave, the contents were admixed with 100ml of ethyl acetate and the resulting phases were separated. The aqueousphase was extracted twice with 100 ml of ethyl acetate each time, thecombined organic phases were dried over Na₂SO₄ and the solvent wasremoved under reduced pressure.

[0241] The residue was dissolved in 250 ml of cyclohexane/ethyl acetate(1:1) to remove 2,6-diaminopyridine which had formed, filtered togetherwith a further 250 ml of cyclohexane/ethyl acetate (1:1) through a shortsilica gel column (5×20 cm), and freed of solvent under reducedpressure. Sublimation of the residue at 90° C. and 10⁻¹ mbar afforded6.49 g (37.5 mmol, 88.9%) of 6-bromo-2-aminopyridine as a white solid.

[0242] 14.2 Electrophilic Route

[0243] 14.2.1 Preparation of 6-bromo-2-pivaloylaminopyridine

[0244] 4.0 g (23.1 mmol) of 6-bromo-2-aminopyridine from example 14.1were dissolved in 25 ml of dichloromethane and admixed with 4.1 ml (2.92g, 28.9 mmol) of triethylamine. After cooling to 0° C., a solution of3.1 ml (3.06 g, 25.4 mmol) of pivaloyl chloride in 5.0 ml ofdichloromethane was added dropwise over a period of 10 min. The reactionmixture was allowed to warm to room temperature overnight and, forworkup, poured onto 100 ml of dist. H₂O. The phases were separated, theaqueous phase was extracted twice with 100 ml each time of ethyl acetateand the combined organic phases were dried over Na₂SO₄. The solvent wasremoved under reduced pressure, and the residue was dissolved indichloromethane and filtered through a short silica gel column (3×10cm). After the solvent had been removed under reduced pressure, 5.73 g(22.3 mmol, 96.5%) of 6-bromo-2-pivaloylaminopyridine were obtained as awhite solid.

[0245] 14.2.2 Preparation of6-(diphenylphosphino)-2-pivaloylaminopyridine [6-DPPAP]

[0246] 1.00 g (3.89 mmol) of 6-bromo-2-pivaloylaminopyridine fromexample 14.2.1 was dissolved in 10 ml of diethyl ether and admixed at 0°C. with 3.64 ml (8.00 mmol) of (iso-C₃H₇)MgBr (2.2M in Et₂O). Thesuspension was stirred at 0° C. for 18 h and then admixed with 0.7 ml(0.86 g, 3.89 mmol) of chlorodiphenylphosphine. The mixture was allowedto warm to ambient temperature overnight and was then hydrolyzed byadding 10 ml of dist. H₂O. The resulting phases were separated and theaqueous phase was extracted twice with 50 ml each time of ethyl acetate.The organic phases were combined and dried over Na₂SO₄, and the solventwas removed under reduced pressure. The residue was filtered togetherwith dichloromethane through a short silica gel column (2×10 cm) and thesolvent was removed under reduced pressure. The resulting oil wascrystallized by digesting with petroleum ether/diethyl ether (40/60).The crystals were filtered off and washed with petroleum ether/diethylether (40/60). 0.38 g (1.05 mmol, 27.0%) of6-(diphenylphosphino)-2-pivaloylaminopyridine was obtained as a solid.

[0247]³¹P NMR (121.5 MHz, C₆D₆): δ[ppm]=−3.9

[0248] 14.3 Nucleophilic Route

[0249] 14.3.1 Preparation of 6-(diphenylphosphino)-2-aminopyridine[6-DPAP]

[0250] At −78° C., 200 ml of ammonia were condensed in and 5.00 g ofsodium (216.8 mmol) were dissolved therein within 5 min. The resultingdark blue solution was admixed with 11.70 g of triphenylphosphine (108.4mmol) in portions, stirred at −78° C. for approx. 2 h and then admixedwith 15.00 g (86.7 mmol) of 6-bromo-2-aminopyridine from example 14.1.After 250 ml of toluene had been added, the cold bath was removed andthe ammonia evaporated off overnight. The residue was hydrolyzed with150 ml of dist. H₂O and admixed with 150 ml of saturated NaCl solution,the resulting phases were separated and the aqueous phase was extractedonce with 200 ml of toluene. The combined organic phases were dried overMgSO₄ and concentrated under reduced pressure. The product was purifiedby column chromatography (first with dichloromethane to removediphenylphosphine, then with 9:1 dichloromethane/ethyl acetate).Resulting mixed fractions were purified by sublimation at 180° C. and10⁻² mbar. 14.26 g (51.2 mmol, 59%) of6-(diphenylphosphino)-2-aminopyridine were obtained as a white solid.

[0251]³¹P NMR (121.5 MHz, C₆D₆): δ[ppm]=−3.7

[0252]14.3.2 Preparation of6-(diphenylphosphino)-2-pivaloylaminopyridine

[0253] 2.0 g (7.2 mmol) of 6-(diphenylphosphino)-2-aminopyridine fromexample 14.3.1 were dissolved in 40 ml of dichloromethane and admixedwith 1.6 ml (1.2 g, 10.8 mmol) of triethylamine and 0.16 g (0.7 mmol) of4-dimethylaminopyridine (DMAP). After cooling to 0° C. (H₂O/ice), 1.2 ml(1.2 g, 8.8 mmol) of pivaloyl chloride were slowly added dropwise andthe mixture was kept at this temperature for 3 h. The mixture wasallowed to warm to room temperature overnight and the solvent was thenremoved under reduced pressure. The residue was purified by filtrationtogether with cyclohexane/ethyl acetate (1:1) through a short silica gelcolumn (3×10 cm). The solvent was removed under reduced pressure and theresulting oil crystallized by digesting with petroleum ether (40/60).The solid was filtered off, washed with petroleum ether (40/60) anddried under reduced pressure. 2.25 g (6.2 mmol, 86.1%) of6-(diphenylphosphino)-2-pivaloylaminopyridine were obtained as abeige-colored solid.

[0254]³¹P NMR (121.5 MHz, C₆D₆): δ[ppm]=−3.9

[0255]FIG. 2 shows an ORTEP diagram of the determined crystal structureof 6-(diphenylphosphino)-2-pivaloylaminopyridine.

EXAMPLE 15 Preparation of 6-(diphenylphosphino)-2-acetylaminopyridine[6-DPAAP]

[0256]

[0257] 0.10 g (0.36 mmol) of 6-(diphenylphosphino)-2-aminopyridine fromexample 14.3.1 was dissolved in 2.0 ml of dichloromethane and admixedwith 0.05 ml (0.04 g, 0.40 mmol) of triethylamine and a spatula-tip ofDMAP. After 0.04 ml (0.04 g, 0.40 mmol) of acetic anhydride had beenadded, the mixture was stirred at room temperature for 2 h and then thesolvent was removed under reduced pressure. The residue was purified bycolumn chromatography with cyclohexane/ethyl acetate (1:1). 0.074 g(0.23 mmol, 63.9%) of 6-(diphenylphosphino)-2-acetylaminopyridine wasobtained as a beige-colored solid.

[0258]³¹P NMR (121.5 MHz, C₆D₆): δ[ppm]=−3.2

EXAMPLE 16 Preparation of 3-(diphenylphosphino)isoquinolin-1(2H)-one[3-DPICon]

[0259] 16.1 Preparation of o-cyanomethylbenzoic acid

[0260] 5.0 g (37.3 mmol) of phthalide and 5.0 g (76.8 mmol) of potassiumcyanide, finely ground with a mortar and under vigorous stirring, wereheated to 180° C. for 3.5 h in an open round-bottom flask. In the courseof this, the melt darkened in color and had solidified after thereaction time. The solid was dissolved in 50 ml of dist. H₂O and thesolution was extracted twice with 100 ml each time of ethyl acetate. Thecombined organic phases contain unconverted phthalide and werediscarded. The aqueous phase was admixed with 5.0 g of FeSO₄.7H₂O inorder to bind excess cyanide and acidified with concentrated HCl down toa pH of 2. The precipitated solid was filtered off with suction througha frit filled with kieselguhr and washed with ethyl acetate, and thefiltrate was transferred to a separating funnel. After phase separation,the aqueous phase was extracted twice more with 100 ml each time ofethyl acetate, the combined organic phases were dried over MgSO₄ and thesolvent was removed under reduced pressure. 5.34 g (33.1 mmol, 88.7%) ofo-cyanomethylbenzoic acid were obtained and were used for the followingreaction without further purification.

[0261] 16.2 Preparation of 1,3-dichloroisoquinoline

[0262] 1.3 g (6.24 mmol) of phosphorus pentachloride were dissolved in 6ml of phosphoryl chloride and admixed with 1.0 g (6.21 mmol) ofo-cyanomethylbenzoic acid from example 16.1 in portions. After stirringat room temperature for 90 min, all had dissolved, and the solution washeated to 70° C. for 16 h. After the mixture had been cooled, it waspoured cautiously onto 50 g of ice and admixed with 50 ml of ethylacetate. The phases were separated and the aqueous phase was extractedtwice with 50 ml each time of acetic acid. The combined organic phaseswere washed with 50 ml of H₂O and 50 ml of saturated NaHCO₃ solution,and dried over MgSO₄, and the solvent was removed under reducedpressure. The brown, crystalline crude product was purified by filteringtogether with dichloromethane/cyclohexane (1:1) through a short silicagel column (2×15 cm). 1.04 g (5.25 mmol, 84.5%) of1,3-dichloroisoquinoline were obtained.

[0263] 16.3 Preparation of 1-t-butoxy-3-chloroisoquinoline

[0264] 1.0 g (5.05 mmol) of 1,3-dichloroisoquinoline from example 16.2was dissolved in 20 ml of dry toluene, admixed with 0.68 g (6.06 mmol)of potassium tert-butoxide and stirred at 80° C. for 3 h. After themixture had been cooled, it was filtered together with 50 ml ofdichloromethane through a short silica gel column (1×5 cm) and thesolvent was removed under reduced pressure. 1.06 g (4.50 mmol, 89.1%) of1-t-butoxy-3-chloroisoquinoline were obtained.

[0265] 16.4 Preparation of 3-chloroisoquinolin-1(2H)-one

[0266] 0.5 g (2.12 mmol) of 1-t-butoxy-3-chloroisoquinoline from example16.3 was dissolved in 5.0 ml of formic acid and stirred at roomtemperature for 20 h. The solution was then diluted with 10 ml of H₂O,and the precipitated solid was filtered off through a glass frit, washedwith 10 ml of H₂O/formic acid (2:1) and dried under high vacuum. 0.30 g(1.67 mmol, 78.8%) of 3-chloroisoquinolin-1(2H)-one was obtained. Thecombined aqueous phases were concentrated to dryness under reducedpressure and the resulting solid was purified by column chromatography(5:1 dichloromethane/ethyl acetate), whereupon a further 0.040 g (0.22mmol, 10.4%) of 3-chloroisoquinolin-1(2H)-one was obtained.

[0267] 16.5 Preparation of 3-(diphenylphosphino)isoquinolin-1(2H)-one[3-DPICon]

[0268] At −78° C., 130 ml of ammonia were condensed in and 2.10 g ofsodium (91.3 mmol) were dissolved therein within 5 min. The dark bluesolution was admixed with 11.70 g of triphenylphosphine (44.6 mmol) inportions and stirred at −78° C. for 2 h. After 100 ml of drytetrahydrofuran had been added, the cold bath was removed and theammonia evaporated off within 2 h. After the orange-colored solution hadbeen warmed to room temperature, it was admixed with 4.0 g (22.3 mmol)of 3-chloroisoquinolin-1(2H)-one from example 16.4 in portions andheated to 60° C. for 20 h. After the mixture had been cooled, it wasadmixed with 50 ml of dist. H₂O, and the aqueous phase was extractedthree times with 100 ml each time of dichloromethane, and the combinedorganic phases were dried over MgSO₄ and concentrated under reducedpressure. The resulting solid was digested with dichloromethane,filtered off and dried. The filtrate was concentrated and the resultingsolid again digested with dichloromethane, filtered off and dried. Thesolids were combined. 4.47 g (13.6 mmol, 60.9%) of3-(diphenyl-phosphino)isoquinolin-1(2 H)-one were obtained. The filtratewas concentrated under reduced pressure and the resulting solid purifiedby column chromatography (5:1 dichloromethane/ethyl acetate). A further0.216 g (0.66 mmol, 2.9%) of 3-(diphenylphosphino)isoquinolin-1(2 H)-onewas obtained.

[0269]³¹P NMR (121.5 MHz, C₆D₆): δ[ppm]=−8.7

[0270]FIG. 3 shows an ORTEP diagram of the determined crystal structureof 3-(diphenyl-phosphino)isoquinolin-1(2H)-one.

EXAMPLE 17 Preparation of 2-diphenylphosphinopyridine [2-DPP]

[0271] The synthesis was effected to the method described in similarlyJ. Am. Chem. Soc. 1984, 106(5), 1323-32.

EXAMPLE 18 Crystal Structure Analysis of[cis-PtCl₂(6-DPPAP)(3-DPICon)(H₂O)]

[0272] A Schlenk tube was initially charged with 37.4 mg (100 μmol) of[cis-PtCl₂(COD)], 36.2 mg (100 μmol) of6-(diphenylphosphino)-2-pivaloylaminopyridine and 32.9 mg (100 μmol) of3-(diphenylphosphino)isoquinolin-1(2H)-one, which were admixed with 4.0ml of toluene and dissolved by heating to approx. 80° C. In the courseof cooling, the platinum complex precipitated out as a white solid. Thetoluene was decanted off, the residue was washed twice with 3 ml eachtime of pentane and the white solid was dried under high vacuum.Suitable crystals for a crystal structure analysis were obtained from asolution of 10 mg of [cis-PtCl₂(6-DPPAP)(3-DPICon)(H₂O)] in 1.0 ml oftoluene.

[0273]FIG. 4 shows an ORTEP diagram of the determined crystal structure.

EXAMPLE 19 Hydroformylation of 1-octene

[0274] 1.8 mg (6.98 μmol) of [Rh(CO)₂acac] were dissolved in 10 ml oftoluene and admixed with 0.14 mmol of the particular ligand or their 1:1mixture (heterodimers). The solution was stirred for 5 min, gentlyheated if necessary for complete dissolution and then admixed with 1.1ml (0.78 g, 6.98 mmol) of 1-octene. The solution was transferred to theautoclave, 10 bar of CO/H₂ (1:1) were injected and the autoclave washeated to 70° C. After 20 h, the reaction was stopped by cooling to roomtemperature and decompressing the autoclave. The autoclave effluent wasanalyzed by GC and ¹H NMR spectroscopy. Ligand(s) Linear:branched ratioConversion [%] 2-DPP/3-DPICon  87:13 quantitative 2-DPAAP/3-DPICon 95:5quantitative 2-DPPAP/3-DPICon 94:6 quantitative

EXAMPLE 20 Hydroformylation of Different Substrates Using2-DPPAP/3-DPICon

[0275] 1.8 mg (6.98 μmol) of [Rh(CO)₂acac] were dissolved in 10 ml oftoluene and admixed with 0.14 mmol of the two ligands (1:1 mixture). Thesolution was stirred for 5 min, gently heated if necessary for completedissolution and then admixed with 6.98 mmol of the particular substrate.The solution was transferred to the autoclave, 10 bar of CO/H₂ (1:1)were injected and the autoclave was heated to 70° C. After 20 h, thereaction was stopped by cooling to room temperature and decompressingthe autoclave. The solution was filtered through a little silica geltogether with approx. 50 ml of ethyl acetate and concentrated underreduced pressure. The crude products were analyzed by means of ¹H and¹³C NMR spectroscopy. Substrate Linear:branched ratio Conversion [%]

95:5 quantitative

94:6 quantitative

93:7 quantitative

EXAMPLE 21 Quantum Chemistry Calculations

[0276] Method: B-P86/SV(P) P—P Stable distance Ligand 1 Ligand 2 dimer[Å]

yes 3.75

yes 3.77

yes 3.81

yes 3.82

1. A process for hydroformylating compounds which contain at least oneethylenically unsaturated double bond by reacting with carbon monoxideand hydrogen in the presence of a catalyst comprising at least onecomplex of a metal of transition group VIII of the Periodic Table of theElements with ligands which each have a phosphorus group and at leastone functional group which is capable of forming intermolecularnoncovalent bonds, wherein the complex has ligands which are dimerizedvia intermolecular noncovalent bonds and wherein the distance betweenthe phosphorus atoms of the dimerized ligands is at most 5 Å.
 2. Aprocess as claimed in claim 1, wherein the distance between thephosphorus atoms of the dimerized ligands is in the range from 2.5 to4.5 Å, preferably from 3.5 to 4.2 Å, especially from 3.6 to 4.1 Å.
 3. Aprocess as claimed in claim 1, wherein the functional groups which arecapable of forming intermolecular noncovalent bonds are selected fromhydroxyl, primary, secondary and tertiary amino, thiol, keto,thioketone, imine, carboxylic ester, carboxamide, amidine, urethane,urea, sulfoxide, sulfoximine, sulfonamide and sulfonic ester groups. 4.A process as claimed in claim 1, wherein the functional groups which arecapable of forming intermolecular noncovalent bonds are selected fromgroups which are capable of tautomerizing.
 5. A process as claimed inclaim 1, wherein the ligands include at least one structural element ofthe general formulae I.a or I.b

or tautomers thereof where R¹ and R² are each independently alkyl,alkoxy, cycloalkyl, cycloalkoxy, heterocycloalkyl, heterocycloalkoxy,aryl, aryloxy, hetaryl or hetaryloxy, R³ is hydrogen or is as definedfor R¹ and R², X is a bivalent bridging group having from 1 to 5bridging atoms between the flanking bonds, Y is O, S or NR⁴, where R⁴ ishydrogen, alkyl, cycloalkyl, heterocycloalkyl, aryl or hetaryl, and twoor more than two of the X radicals and R¹ to R⁴ together with thestructural element of the formula I.a or I.b to which they are bondedmay be a mono- or polycyclic compound.
 6. A process as claimed in claim5, wherein R¹ and R² in the ligands I.a or I.b, together with thephosphorus atom to which they are bonded, are each a 5- to 8-memberedheterocycle which may optionally additionally be singly, doubly ortriply fused with cycloalkyl, heterocycloalkyl, aryl or hetaryl, and theheterocycle and, where present, the fused groups may each independentlybear one, two, three or four substituents which are selected from alkyl,cycloalkyl, heterocycloalkyl, aryl, hetaryl, COOR^(c), COO⁻M⁺, SO₃R^(c),SO₃ ⁻M⁺,PO₃(R^(c))(R^(d)), (PO₃)²⁻(M⁺)₂, NE⁴E⁵, (NE⁴E⁵E⁶)⁺X⁻, OR^(e),SR^(e), (CHR^(f)CH₂O)_(y)R^(e), (CH₂NE⁴)_(y)R^(e), (CH₂CH₂NE⁴)_(y)R^(e),halogen, nitro, acyl and cyano, where R^(c) and R^(d) are each identicalor different radicals selected from alkyl, cycloalkyl, aryl and hetaryl,R^(e), E⁴, E⁵, E⁶ are each identical or different radicals selected fromhydrogen, alkyl, cycloalkyl, acyl, aryl and hetaryl, R^(f) is hydrogen,methyl or ethyl, M⁺ is one cation equivalent, X⁻ is one anion equivalentand y is an integer from 1 to
 240. 7. A process as claimed in claim 1,wherein the ligands are selected from compounds of the general formulaeI.1 to I.3

and the tautomers thereof where one of the R⁵ to R⁹ radicals is a groupof the formula —W′—PR¹R² whereW′ is a single bond, a heteroatom, aheteroatom-containing group or a bivalent bridging group having from 1to 4 bridging atoms between the flanking bonds, R¹ and R² are each asdefined in either of claims 4 or 5, the R⁵ to R⁹ radicals which are not—W′—PR¹R² are each independently hydrogen, alkyl, cycloalkyl,heterocycloalkyl, aryl, hetaryl, WCOOR^(o), WCOO⁻M⁺, W(SO₃)R^(o),W(SO₃)⁻M⁺, WPO₃(R^(o))(R^(p)), W(PO₃)²⁻(M⁺)₂, WNE¹E², W(NE¹E²E³)⁺X⁻,WOR^(q), WSR^(q), (CHR^(r)CH₂O)_(x)R^(q), (CH₂NE¹)_(x)R^(q),(CH₂CH₂NE¹)_(x)R^(q), halogen, nitro, acyl or cyano, where W is a singlebond, a heteroatom, a heteroatom-containing group or a bivalent bridginggroup having from 1 to 20 bridging atoms, R^(o) and R^(p) are eachidentical or different radicals selected from alkyl, cycloalkyl, aryland hetaryl, R^(q), E¹, E², E³ are each identical or different radicalsselected from hydrogen, alkyl, cycloalkyl, acyl, aryl and hetaryl, R^(r)is hydrogen, methyl or ethyl, M⁺ is one cation equivalent, X⁻ is oneanion equivalent and x is an integer from 1 to 240, and in each case twoadjacent R⁵, R⁶, R⁷, R⁸ and R⁹ radicals, together with the ring carbonatoms to which they are bonded, may also be a fused ring system having1, 2 or 3 further rings, and R^(a) and R^(b) are each hydrogen, alkyl,acyl, cycloalkyl, heterocycloalkyl, aryl or hetaryl.
 8. A process forhydroformylating compounds which contain at least one ethylenicallyunsaturated double bond by reacting with carbon monoxide and hydrogen inthe presence of a catalyst comprising at least one complex of a metal oftransition group VIII of the Periodic Table of the Elements with ligandswhich are selected from compounds of the general formulae I.1 to I.3

and the tautomers thereof where one of the R⁵ to R⁹ radicals is a groupof the formula —W′—PR¹R² whereW′ is a single bond, a heteroatom, aheteroatom-containing group or a bivalent bridging group having from 1to 4 bridging atoms between the flanking bonds, R¹ and R² are each asdefined in either of claims 4 or 5, the R⁵ to R⁹ radicals which are not—W′—PR¹R² are each independently hydrogen, alkyl, cycloalkyl,heterocycloalkyl, aryl, hetaryl, WCOOR^(o), WCOO⁻M⁺, W(SO₃)R^(o),W(SO₃)⁻M⁺, WPO₃(R^(o))(R^(p)), W(PO₃)²⁻(M⁺)₂, WNE¹E², W(NE¹E²E³)⁺X⁻,WOR^(q), WSR^(q), (CHR^(r)CH₂O)_(x)R^(q), (CH₂NE¹)_(x)R^(q),(CH₂CH₂NE¹)_(x)R^(q), halogen, nitro, acyl or cyano, where W is a singlebond, a heteroatom, a heteroatom-containing group or a bivalent bridginggroup having from 1 to 20 bridging atoms, R^(o) and R^(p) are eachidentical or different radicals selected from alkyl, cycloalkyl, aryland hetaryl, R^(q), E¹, E², E³ are each identical or different radicalsselected from hydrogen, alkyl, cycloalkyl, acyl, aryl and hetaryl, R^(r)is hydrogen, methyl or ethyl, M⁺ is one cation equivalent, X⁻ is oneanion equivalent and x is an integer from 1 to 240,  and in each casetwo adjacent R⁵, R⁶, R7, R⁸ and R⁹ radicals, together with the ringcarbon atoms to which they are bonded, may also be a fused ring systemhaving 1, 2 or 3 further rings, and R^(a) and R^(b) are each hydrogen,alkyl, acyl, cycloalkyl, heterocycloalkyl, aryl or hetaryl.
 9. A processas claimed in claim 6, wherein the ligands are selected from compoundsof the general formulae I.i to I.iii

and the tautomers thereof where a is 0 or 1, R¹ and R² are each asdefined above, R⁶ to R⁹ are each independently hydrogen, C₁-C₄-alkyl,C₁-C₄-alkoxy, acyl, aryl, heteroaryl, halogen, C₁-C₄-alkoxycarbonyl orcarboxylate,  and in each case two adjacent R⁶, R⁷, R⁸ and R⁹ radicals,together with the ring carbon atoms to which they are bonded, may alsobe a fused ring system having 1, 2 or 3 further rings, and R^(a) andR^(b) are each hydrogen, alkyl, acyl, cycloalkyl or aryl.
 10. A processas claimed in claim 1, wherein the ligands used comprise at least onecompound of the formulae (1) to (4)


11. A process as claimed in claim 1, wherein the ligand used is one ofthe following ligands/ligand pairs (5) to (8): (5)

(6)

(7)

(8)


12. A catalyst as defined in claim
 1. 13. A catalyst as claimed in claim12, wherein the metal is selected from cobalt, nickel, rhodium,ruthenium and iridium.
 14. A process for preparing 2-propylheptanol, bya) hydroformylating butene or a butene-containing C₄ hydrocarbon mixturein the presence of a catalyst as defined in claim 12 with carbonmonoxide and hydrogen to obtain an n-valeraldehyde-containinghydroformylation product, b) optionally subjecting the hydroformylationproduct to a separation to obtain an n-valeraldehyde-enriched fraction,c) subjecting the hydroformylation product obtained in step a) or then-valeraldehyde-enriched fraction obtained in step b) to an aldolcondensation, d) catalytically hydrogenating the products of the aldolcondensation with hydrogen to give alcohols, and e) optionallysubjecting the hydrogenation products to a separation to obtain a2-propylheptanol-enriched fraction.
 15. A process for preparing an estermixture, wherein an alcohol mixture obtainable by a process as definedin claim 14 is reacted with at least one acid which is selected fromaliphatic di- and tricarboxylic acids, aromatic mono-, di- andtricarboxylic acids, phosphoric acid and derivatives and mixturesthereof. 16 (canceled)